linux-toradex.git/net/core/dev.c, branch v4.4.93 Linux kernel for Apalis and Colibri modules net: core: Prevent from dereferencing null pointer when releasing SKB 2017-10-08T08:14:18+00:00 Myungho Jung mhjungk@gmail.com 2017-04-25T18:58:15+00:00 b9ff317b5cd4a8f7ca13934af679e129c3f1d2ce [ Upstream commit 9899886d5e8ec5b343b1efe44f185a0e68dc6454 ] Added NULL check to make __dev_kfree_skb_irq consistent with kfree family of functions. Link: https://bugzilla.kernel.org/show_bug.cgi?id=195289 Signed-off-by: Myungho Jung <mhjungk@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 9899886d5e8ec5b343b1efe44f185a0e68dc6454 ]

Added NULL check to make __dev_kfree_skb_irq consistent with kfree
family of functions.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=195289

Signed-off-by: Myungho Jung <mhjungk@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: avoid skb_warn_bad_offload false positives on UFO 2017-08-13T02:29:08+00:00 Willem de Bruijn willemb@google.com 2017-08-08T18:22:55+00:00 37d5c6e8d38d674b1c25741fdf033f7f00b5ed5f [ Upstream commit 8d63bee643f1fb53e472f0e135cae4eb99d62d19 ] skb_warn_bad_offload triggers a warning when an skb enters the GSO stack at __skb_gso_segment that does not have CHECKSUM_PARTIAL checksum offload set. Commit b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise") observed that SKB_GSO_DODGY producers can trigger the check and that passing those packets through the GSO handlers will fix it up. But, the software UFO handler will set ip_summed to CHECKSUM_NONE. When __skb_gso_segment is called from the receive path, this triggers the warning again. Make UFO set CHECKSUM_UNNECESSARY instead of CHECKSUM_NONE. On Tx these two are equivalent. On Rx, this better matches the skb state (checksum computed), as CHECKSUM_NONE here means no checksum computed. See also this thread for context: http://patchwork.ozlabs.org/patch/799015/ Fixes: b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise") Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 8d63bee643f1fb53e472f0e135cae4eb99d62d19 ]

skb_warn_bad_offload triggers a warning when an skb enters the GSO
stack at __skb_gso_segment that does not have CHECKSUM_PARTIAL
checksum offload set.

Commit b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise")
observed that SKB_GSO_DODGY producers can trigger the check and
that passing those packets through the GSO handlers will fix it
up. But, the software UFO handler will set ip_summed to
CHECKSUM_NONE.

When __skb_gso_segment is called from the receive path, this
triggers the warning again.

Make UFO set CHECKSUM_UNNECESSARY instead of CHECKSUM_NONE. On
Tx these two are equivalent. On Rx, this better matches the
skb state (checksum computed), as CHECKSUM_NONE here means no
checksum computed.

See also this thread for context:
http://patchwork.ozlabs.org/patch/799015/

Fixes: b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: skb_needs_check() accepts CHECKSUM_NONE for tx 2017-08-07T02:19:43+00:00 Eric Dumazet edumazet@google.com 2017-02-03T22:29:42+00:00 fa57125e8ec40cdb00607b9e4a1dca2a30612084 commit 6e7bc478c9a006c701c14476ec9d389a484b4864 upstream. My recent change missed fact that UFO would perform a complete UDP checksum before segmenting in frags. In this case skb->ip_summed is set to CHECKSUM_NONE. We need to add this valid case to skb_needs_check() Fixes: b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6e7bc478c9a006c701c14476ec9d389a484b4864 upstream.

My recent change missed fact that UFO would perform a complete
UDP checksum before segmenting in frags.

In this case skb->ip_summed is set to CHECKSUM_NONE.

We need to add this valid case to skb_needs_check()

Fixes: b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: reduce skb_warn_bad_offload() noise 2017-08-07T02:19:38+00:00 Eric Dumazet edumazet@google.com 2017-01-31T18:20:32+00:00 fdbcb81b5a319dd3e34105a2793c1189bdbfa646 commit b2504a5dbef3305ef41988ad270b0e8ec289331c upstream. Dmitry reported warnings occurring in __skb_gso_segment() [1] All SKB_GSO_DODGY producers can allow user space to feed packets that trigger the current check. We could prevent them from doing so, rejecting packets, but this might add regressions to existing programs. It turns out our SKB_GSO_DODGY handlers properly set up checksum information that is needed anyway when packets needs to be segmented. By checking again skb_needs_check() after skb_mac_gso_segment(), we should remove these pesky warnings, at a very minor cost. With help from Willem de Bruijn [1] WARNING: CPU: 1 PID: 6768 at net/core/dev.c:2439 skb_warn_bad_offload+0x2af/0x390 net/core/dev.c:2434 lo: caps=(0x000000a2803b7c69, 0x0000000000000000) len=138 data_len=0 gso_size=15883 gso_type=4 ip_summed=0 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 6768 Comm: syz-executor1 Not tainted 4.9.0 #5 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801c063ecd8 ffffffff82346bdf ffffffff00000001 1ffff100380c7d2e ffffed00380c7d26 0000000041b58ab3 ffffffff84b37e38 ffffffff823468f1 ffffffff84820740 ffffffff84f289c0 dffffc0000000000 ffff8801c063ee20 Call Trace: [<ffffffff82346bdf>] __dump_stack lib/dump_stack.c:15 [inline] [<ffffffff82346bdf>] dump_stack+0x2ee/0x3ef lib/dump_stack.c:51 [<ffffffff81827e34>] panic+0x1fb/0x412 kernel/panic.c:179 [<ffffffff8141f704>] __warn+0x1c4/0x1e0 kernel/panic.c:542 [<ffffffff8141f7e5>] warn_slowpath_fmt+0xc5/0x100 kernel/panic.c:565 [<ffffffff8356cbaf>] skb_warn_bad_offload+0x2af/0x390 net/core/dev.c:2434 [<ffffffff83585cd2>] __skb_gso_segment+0x482/0x780 net/core/dev.c:2706 [<ffffffff83586f19>] skb_gso_segment include/linux/netdevice.h:3985 [inline] [<ffffffff83586f19>] validate_xmit_skb+0x5c9/0xc20 net/core/dev.c:2969 [<ffffffff835892bb>] __dev_queue_xmit+0xe6b/0x1e70 net/core/dev.c:3383 [<ffffffff8358a2d7>] dev_queue_xmit+0x17/0x20 net/core/dev.c:3424 [<ffffffff83ad161d>] packet_snd net/packet/af_packet.c:2930 [inline] [<ffffffff83ad161d>] packet_sendmsg+0x32ed/0x4d30 net/packet/af_packet.c:2955 [<ffffffff834f0aaa>] sock_sendmsg_nosec net/socket.c:621 [inline] [<ffffffff834f0aaa>] sock_sendmsg+0xca/0x110 net/socket.c:631 [<ffffffff834f329a>] ___sys_sendmsg+0x8fa/0x9f0 net/socket.c:1954 [<ffffffff834f5e58>] __sys_sendmsg+0x138/0x300 net/socket.c:1988 [<ffffffff834f604d>] SYSC_sendmsg net/socket.c:1999 [inline] [<ffffffff834f604d>] SyS_sendmsg+0x2d/0x50 net/socket.c:1995 [<ffffffff84371941>] entry_SYSCALL_64_fastpath+0x1f/0xc2 Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Mark Salyzyn <salyzyn@android.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b2504a5dbef3305ef41988ad270b0e8ec289331c upstream.

Dmitry reported warnings occurring in __skb_gso_segment() [1]

All SKB_GSO_DODGY producers can allow user space to feed
packets that trigger the current check.

We could prevent them from doing so, rejecting packets, but
this might add regressions to existing programs.

It turns out our SKB_GSO_DODGY handlers properly set up checksum
information that is needed anyway when packets needs to be segmented.

By checking again skb_needs_check() after skb_mac_gso_segment(),
we should remove these pesky warnings, at a very minor cost.

With help from Willem de Bruijn

[1]
WARNING: CPU: 1 PID: 6768 at net/core/dev.c:2439 skb_warn_bad_offload+0x2af/0x390 net/core/dev.c:2434
lo: caps=(0x000000a2803b7c69, 0x0000000000000000) len=138 data_len=0 gso_size=15883 gso_type=4 ip_summed=0
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 6768 Comm: syz-executor1 Not tainted 4.9.0 #5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801c063ecd8 ffffffff82346bdf ffffffff00000001 1ffff100380c7d2e
 ffffed00380c7d26 0000000041b58ab3 ffffffff84b37e38 ffffffff823468f1
 ffffffff84820740 ffffffff84f289c0 dffffc0000000000 ffff8801c063ee20
Call Trace:
 [<ffffffff82346bdf>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff82346bdf>] dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
 [<ffffffff81827e34>] panic+0x1fb/0x412 kernel/panic.c:179
 [<ffffffff8141f704>] __warn+0x1c4/0x1e0 kernel/panic.c:542
 [<ffffffff8141f7e5>] warn_slowpath_fmt+0xc5/0x100 kernel/panic.c:565
 [<ffffffff8356cbaf>] skb_warn_bad_offload+0x2af/0x390 net/core/dev.c:2434
 [<ffffffff83585cd2>] __skb_gso_segment+0x482/0x780 net/core/dev.c:2706
 [<ffffffff83586f19>] skb_gso_segment include/linux/netdevice.h:3985 [inline]
 [<ffffffff83586f19>] validate_xmit_skb+0x5c9/0xc20 net/core/dev.c:2969
 [<ffffffff835892bb>] __dev_queue_xmit+0xe6b/0x1e70 net/core/dev.c:3383
 [<ffffffff8358a2d7>] dev_queue_xmit+0x17/0x20 net/core/dev.c:3424
 [<ffffffff83ad161d>] packet_snd net/packet/af_packet.c:2930 [inline]
 [<ffffffff83ad161d>] packet_sendmsg+0x32ed/0x4d30 net/packet/af_packet.c:2955
 [<ffffffff834f0aaa>] sock_sendmsg_nosec net/socket.c:621 [inline]
 [<ffffffff834f0aaa>] sock_sendmsg+0xca/0x110 net/socket.c:631
 [<ffffffff834f329a>] ___sys_sendmsg+0x8fa/0x9f0 net/socket.c:1954
 [<ffffffff834f5e58>] __sys_sendmsg+0x138/0x300 net/socket.c:1988
 [<ffffffff834f604d>] SYSC_sendmsg net/socket.c:1999 [inline]
 [<ffffffff834f604d>] SyS_sendmsg+0x2d/0x50 net/socket.c:1995
 [<ffffffff84371941>] entry_SYSCALL_64_fastpath+0x1f/0xc2

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov  <dvyukov@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Mark Salyzyn <salyzyn@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: handle NAPI_GRO_FREE_STOLEN_HEAD case also in napi_frags_finish() 2017-07-21T05:44:55+00:00 Michal Kubeček mkubecek@suse.cz 2017-06-29T09:13:36+00:00 38ae32c9f13d3f0c642d373f35489752aa60d466 commit e44699d2c28067f69698ccb68dd3ddeacfebc434 upstream. Recently I started seeing warnings about pages with refcount -1. The problem was traced to packets being reused after their head was merged into a GRO packet by skb_gro_receive(). While bisecting the issue pointed to commit c21b48cc1bbf ("net: adjust skb->truesize in ___pskb_trim()") and I have never seen it on a kernel with it reverted, I believe the real problem appeared earlier when the option to merge head frag in GRO was implemented. Handling NAPI_GRO_FREE_STOLEN_HEAD state was only added to GRO_MERGED_FREE branch of napi_skb_finish() so that if the driver uses napi_gro_frags() and head is merged (which in my case happens after the skb_condense() call added by the commit mentioned above), the skb is reused including the head that has been merged. As a result, we release the page reference twice and eventually end up with negative page refcount. To fix the problem, handle NAPI_GRO_FREE_STOLEN_HEAD in napi_frags_finish() the same way it's done in napi_skb_finish(). Fixes: d7e8883cfcf4 ("net: make GRO aware of skb->head_frag") Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e44699d2c28067f69698ccb68dd3ddeacfebc434 upstream.

Recently I started seeing warnings about pages with refcount -1. The
problem was traced to packets being reused after their head was merged into
a GRO packet by skb_gro_receive(). While bisecting the issue pointed to
commit c21b48cc1bbf ("net: adjust skb->truesize in ___pskb_trim()") and
I have never seen it on a kernel with it reverted, I believe the real
problem appeared earlier when the option to merge head frag in GRO was
implemented.

Handling NAPI_GRO_FREE_STOLEN_HEAD state was only added to GRO_MERGED_FREE
branch of napi_skb_finish() so that if the driver uses napi_gro_frags()
and head is merged (which in my case happens after the skb_condense()
call added by the commit mentioned above), the skb is reused including the
head that has been merged. As a result, we release the page reference
twice and eventually end up with negative page refcount.

To fix the problem, handle NAPI_GRO_FREE_STOLEN_HEAD in napi_frags_finish()
the same way it's done in napi_skb_finish().

Fixes: d7e8883cfcf4 ("net: make GRO aware of skb->head_frag")
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: prevent sign extension in dev_get_stats() 2017-07-21T05:44:54+00:00 Eric Dumazet edumazet@google.com 2017-06-27T14:02:20+00:00 d598f7ff24db728c7417fb02871aa6578d97e224 commit 6f64ec74515925cced6df4571638b5a099a49aae upstream. Similar to the fix provided by Dominik Heidler in commit 9b3dc0a17d73 ("l2tp: cast l2tp traffic counter to unsigned") we need to take care of 32bit kernels in dev_get_stats(). When using atomic_long_read(), we add a 'long' to u64 and might misinterpret high order bit, unless we cast to unsigned. Fixes: caf586e5f23ce ("net: add a core netdev->rx_dropped counter") Fixes: 015f0688f57ca ("net: net: add a core netdev->tx_dropped counter") Fixes: 6e7333d315a76 ("net: add rx_nohandler stat counter") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Jarod Wilson <jarod@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6f64ec74515925cced6df4571638b5a099a49aae upstream.

Similar to the fix provided by Dominik Heidler in commit
9b3dc0a17d73 ("l2tp: cast l2tp traffic counter to unsigned")
we need to take care of 32bit kernels in dev_get_stats().

When using atomic_long_read(), we add a 'long' to u64 and
might misinterpret high order bit, unless we cast to unsigned.

Fixes: caf586e5f23ce ("net: add a core netdev->rx_dropped counter")
Fixes: 015f0688f57ca ("net: net: add a core netdev->tx_dropped counter")
Fixes: 6e7333d315a76 ("net: add rx_nohandler stat counter")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: don't call strlen on non-terminated string in dev_set_alias() 2017-07-05T12:37:13+00:00 Alexander Potapenko glider@google.com 2017-06-06T13:56:54+00:00 e79948e2d90bfe19267b35850c83c7cd98a78a60 [ Upstream commit c28294b941232931fbd714099798eb7aa7e865d7 ] KMSAN reported a use of uninitialized memory in dev_set_alias(), which was caused by calling strlcpy() (which in turn called strlen()) on the user-supplied non-terminated string. Signed-off-by: Alexander Potapenko <glider@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit c28294b941232931fbd714099798eb7aa7e865d7 ]

KMSAN reported a use of uninitialized memory in dev_set_alias(),
which was caused by calling strlcpy() (which in turn called strlen())
on the user-supplied non-terminated string.

Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: better skb->sender_cpu and skb->napi_id cohabitation 2017-06-14T11:16:26+00:00 Eric Dumazet edumazet@google.com 2015-11-18T14:30:50+00:00 52d8b8ad2b4ba478b55e0dfff56a13ab436a6b65 commit 52bd2d62ce6758d811edcbd2256eb9ea7f6a56cb upstream. skb->sender_cpu and skb->napi_id share a common storage, and we had various bugs about this. We had to call skb_sender_cpu_clear() in some places to not leave a prior skb->napi_id and fool netdev_pick_tx() As suggested by Alexei, we could split the space so that these errors can not happen. 0 value being reserved as the common (not initialized) value, let's reserve [1 .. NR_CPUS] range for valid sender_cpu, and [NR_CPUS+1 .. ~0U] for valid napi_id. This will allow proper busy polling support over tunnels. Signed-off-by: Eric Dumazet <edumazet@google.com> Suggested-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Paul Menzel <pmenzel@molgen.mpg.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 52bd2d62ce6758d811edcbd2256eb9ea7f6a56cb upstream.

skb->sender_cpu and skb->napi_id share a common storage,
and we had various bugs about this.

We had to call skb_sender_cpu_clear() in some places to
not leave a prior skb->napi_id and fool netdev_pick_tx()

As suggested by Alexei, we could split the space so that
these errors can not happen.

0 value being reserved as the common (not initialized) value,
let's reserve [1 .. NR_CPUS] range for valid sender_cpu,
and [NR_CPUS+1 .. ~0U] for valid napi_id.

This will allow proper busy polling support over tunnels.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: net_enable_timestamp() can be called from irq contexts 2017-03-22T11:04:14+00:00 Eric Dumazet edumazet@google.com 2017-03-01T22:28:39+00:00 a70c328597045be2962098916c88ddd172caa054 [ Upstream commit 13baa00ad01bb3a9f893e3a08cbc2d072fc0c15d ] It is now very clear that silly TCP listeners might play with enabling/disabling timestamping while new children are added to their accept queue. Meaning net_enable_timestamp() can be called from BH context while current state of the static key is not enabled. Lets play safe and allow all contexts. The work queue is scheduled only under the problematic cases, which are the static key enable/disable transition, to not slow down critical paths. This extends and improves what we did in commit 5fa8bbda38c6 ("net: use a work queue to defer net_disable_timestamp() work") Fixes: b90e5794c5bd ("net: dont call jump_label_dec from irq context") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 13baa00ad01bb3a9f893e3a08cbc2d072fc0c15d ]

It is now very clear that silly TCP listeners might play with
enabling/disabling timestamping while new children are added
to their accept queue.

Meaning net_enable_timestamp() can be called from BH context
while current state of the static key is not enabled.

Lets play safe and allow all contexts.

The work queue is scheduled only under the problematic cases,
which are the static key enable/disable transition, to not slow down
critical paths.

This extends and improves what we did in commit 5fa8bbda38c6 ("net: use
a work queue to defer net_disable_timestamp() work")

Fixes: b90e5794c5bd ("net: dont call jump_label_dec from irq context")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: use a work queue to defer net_disable_timestamp() work 2017-02-18T15:39:26+00:00 Eric Dumazet edumazet@google.com 2017-02-02T18:31:35+00:00 22449a01baa59fc7fb2a09df26f55faf967828bc [ Upstream commit 5fa8bbda38c668e56b0c6cdecced2eac2fe36dec ] Dmitry reported a warning [1] showing that we were calling net_disable_timestamp() -> static_key_slow_dec() from a non process context. Grabbing a mutex while holding a spinlock or rcu_read_lock() is not allowed. As Cong suggested, we now use a work queue. It is possible netstamp_clear() exits while netstamp_needed_deferred is not zero, but it is probably not worth trying to do better than that. netstamp_needed_deferred atomic tracks the exact number of deferred decrements. [1] [ INFO: suspicious RCU usage. ] 4.10.0-rc5+ #192 Not tainted ------------------------------- ./include/linux/rcupdate.h:561 Illegal context switch in RCU read-side critical section! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 0 2 locks held by syz-executor14/23111: #0: (sk_lock-AF_INET6){+.+.+.}, at: [<ffffffff83a35c35>] lock_sock include/net/sock.h:1454 [inline] #0: (sk_lock-AF_INET6){+.+.+.}, at: [<ffffffff83a35c35>] rawv6_sendmsg+0x1e65/0x3ec0 net/ipv6/raw.c:919 #1: (rcu_read_lock){......}, at: [<ffffffff83ae2678>] nf_hook include/linux/netfilter.h:201 [inline] #1: (rcu_read_lock){......}, at: [<ffffffff83ae2678>] __ip6_local_out+0x258/0x840 net/ipv6/output_core.c:160 stack backtrace: CPU: 2 PID: 23111 Comm: syz-executor14 Not tainted 4.10.0-rc5+ #192 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:15 [inline] dump_stack+0x2ee/0x3ef lib/dump_stack.c:51 lockdep_rcu_suspicious+0x139/0x180 kernel/locking/lockdep.c:4452 rcu_preempt_sleep_check include/linux/rcupdate.h:560 [inline] ___might_sleep+0x560/0x650 kernel/sched/core.c:7748 __might_sleep+0x95/0x1a0 kernel/sched/core.c:7739 mutex_lock_nested+0x24f/0x1730 kernel/locking/mutex.c:752 atomic_dec_and_mutex_lock+0x119/0x160 kernel/locking/mutex.c:1060 __static_key_slow_dec+0x7a/0x1e0 kernel/jump_label.c:149 static_key_slow_dec+0x51/0x90 kernel/jump_label.c:174 net_disable_timestamp+0x3b/0x50 net/core/dev.c:1728 sock_disable_timestamp+0x98/0xc0 net/core/sock.c:403 __sk_destruct+0x27d/0x6b0 net/core/sock.c:1441 sk_destruct+0x47/0x80 net/core/sock.c:1460 __sk_free+0x57/0x230 net/core/sock.c:1468 sock_wfree+0xae/0x120 net/core/sock.c:1645 skb_release_head_state+0xfc/0x200 net/core/skbuff.c:655 skb_release_all+0x15/0x60 net/core/skbuff.c:668 __kfree_skb+0x15/0x20 net/core/skbuff.c:684 kfree_skb+0x16e/0x4c0 net/core/skbuff.c:705 inet_frag_destroy+0x121/0x290 net/ipv4/inet_fragment.c:304 inet_frag_put include/net/inet_frag.h:133 [inline] nf_ct_frag6_gather+0x1106/0x3840 net/ipv6/netfilter/nf_conntrack_reasm.c:617 ipv6_defrag+0x1be/0x2b0 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c:68 nf_hook_entry_hookfn include/linux/netfilter.h:102 [inline] nf_hook_slow+0xc3/0x290 net/netfilter/core.c:310 nf_hook include/linux/netfilter.h:212 [inline] __ip6_local_out+0x489/0x840 net/ipv6/output_core.c:160 ip6_local_out+0x2d/0x170 net/ipv6/output_core.c:170 ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1722 ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1742 rawv6_push_pending_frames net/ipv6/raw.c:613 [inline] rawv6_sendmsg+0x2d1a/0x3ec0 net/ipv6/raw.c:927 inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:744 sock_sendmsg_nosec net/socket.c:635 [inline] sock_sendmsg+0xca/0x110 net/socket.c:645 sock_write_iter+0x326/0x600 net/socket.c:848 do_iter_readv_writev+0x2e3/0x5b0 fs/read_write.c:695 do_readv_writev+0x42c/0x9b0 fs/read_write.c:872 vfs_writev+0x87/0xc0 fs/read_write.c:911 do_writev+0x110/0x2c0 fs/read_write.c:944 SYSC_writev fs/read_write.c:1017 [inline] SyS_writev+0x27/0x30 fs/read_write.c:1014 entry_SYSCALL_64_fastpath+0x1f/0xc2 RIP: 0033:0x445559 RSP: 002b:00007f6f46fceb58 EFLAGS: 00000292 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000445559 RDX: 0000000000000001 RSI: 0000000020f1eff0 RDI: 0000000000000005 RBP: 00000000006e19c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000700000 R13: 0000000020f59000 R14: 0000000000000015 R15: 0000000000020400 BUG: sleeping function called from invalid context at kernel/locking/mutex.c:752 in_atomic(): 1, irqs_disabled(): 0, pid: 23111, name: syz-executor14 INFO: lockdep is turned off. CPU: 2 PID: 23111 Comm: syz-executor14 Not tainted 4.10.0-rc5+ #192 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:15 [inline] dump_stack+0x2ee/0x3ef lib/dump_stack.c:51 ___might_sleep+0x47e/0x650 kernel/sched/core.c:7780 __might_sleep+0x95/0x1a0 kernel/sched/core.c:7739 mutex_lock_nested+0x24f/0x1730 kernel/locking/mutex.c:752 atomic_dec_and_mutex_lock+0x119/0x160 kernel/locking/mutex.c:1060 __static_key_slow_dec+0x7a/0x1e0 kernel/jump_label.c:149 static_key_slow_dec+0x51/0x90 kernel/jump_label.c:174 net_disable_timestamp+0x3b/0x50 net/core/dev.c:1728 sock_disable_timestamp+0x98/0xc0 net/core/sock.c:403 __sk_destruct+0x27d/0x6b0 net/core/sock.c:1441 sk_destruct+0x47/0x80 net/core/sock.c:1460 __sk_free+0x57/0x230 net/core/sock.c:1468 sock_wfree+0xae/0x120 net/core/sock.c:1645 skb_release_head_state+0xfc/0x200 net/core/skbuff.c:655 skb_release_all+0x15/0x60 net/core/skbuff.c:668 __kfree_skb+0x15/0x20 net/core/skbuff.c:684 kfree_skb+0x16e/0x4c0 net/core/skbuff.c:705 inet_frag_destroy+0x121/0x290 net/ipv4/inet_fragment.c:304 inet_frag_put include/net/inet_frag.h:133 [inline] nf_ct_frag6_gather+0x1106/0x3840 net/ipv6/netfilter/nf_conntrack_reasm.c:617 ipv6_defrag+0x1be/0x2b0 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c:68 nf_hook_entry_hookfn include/linux/netfilter.h:102 [inline] nf_hook_slow+0xc3/0x290 net/netfilter/core.c:310 nf_hook include/linux/netfilter.h:212 [inline] __ip6_local_out+0x489/0x840 net/ipv6/output_core.c:160 ip6_local_out+0x2d/0x170 net/ipv6/output_core.c:170 ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1722 ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1742 rawv6_push_pending_frames net/ipv6/raw.c:613 [inline] rawv6_sendmsg+0x2d1a/0x3ec0 net/ipv6/raw.c:927 inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:744 sock_sendmsg_nosec net/socket.c:635 [inline] sock_sendmsg+0xca/0x110 net/socket.c:645 sock_write_iter+0x326/0x600 net/socket.c:848 do_iter_readv_writev+0x2e3/0x5b0 fs/read_write.c:695 do_readv_writev+0x42c/0x9b0 fs/read_write.c:872 vfs_writev+0x87/0xc0 fs/read_write.c:911 do_writev+0x110/0x2c0 fs/read_write.c:944 SYSC_writev fs/read_write.c:1017 [inline] SyS_writev+0x27/0x30 fs/read_write.c:1014 entry_SYSCALL_64_fastpath+0x1f/0xc2 RIP: 0033:0x445559 Fixes: b90e5794c5bd ("net: dont call jump_label_dec from irq context") Suggested-by: Cong Wang <xiyou.wangcong@gmail.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 5fa8bbda38c668e56b0c6cdecced2eac2fe36dec ]

Dmitry reported a warning [1] showing that we were calling
net_disable_timestamp() -> static_key_slow_dec() from a non
process context.

Grabbing a mutex while holding a spinlock or rcu_read_lock()
is not allowed.

As Cong suggested, we now use a work queue.

It is possible netstamp_clear() exits while netstamp_needed_deferred
is not zero, but it is probably not worth trying to do better than that.

netstamp_needed_deferred atomic tracks the exact number of deferred
decrements.

[1]
[ INFO: suspicious RCU usage. ]
4.10.0-rc5+ #192 Not tainted
-------------------------------
./include/linux/rcupdate.h:561 Illegal context switch in RCU read-side
critical section!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 0
2 locks held by syz-executor14/23111:
 #0:  (sk_lock-AF_INET6){+.+.+.}, at: [<ffffffff83a35c35>] lock_sock
include/net/sock.h:1454 [inline]
 #0:  (sk_lock-AF_INET6){+.+.+.}, at: [<ffffffff83a35c35>]
rawv6_sendmsg+0x1e65/0x3ec0 net/ipv6/raw.c:919
 #1:  (rcu_read_lock){......}, at: [<ffffffff83ae2678>] nf_hook
include/linux/netfilter.h:201 [inline]
 #1:  (rcu_read_lock){......}, at: [<ffffffff83ae2678>]
__ip6_local_out+0x258/0x840 net/ipv6/output_core.c:160

stack backtrace:
CPU: 2 PID: 23111 Comm: syz-executor14 Not tainted 4.10.0-rc5+ #192
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs
01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:15 [inline]
 dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
 lockdep_rcu_suspicious+0x139/0x180 kernel/locking/lockdep.c:4452
 rcu_preempt_sleep_check include/linux/rcupdate.h:560 [inline]
 ___might_sleep+0x560/0x650 kernel/sched/core.c:7748
 __might_sleep+0x95/0x1a0 kernel/sched/core.c:7739
 mutex_lock_nested+0x24f/0x1730 kernel/locking/mutex.c:752
 atomic_dec_and_mutex_lock+0x119/0x160 kernel/locking/mutex.c:1060
 __static_key_slow_dec+0x7a/0x1e0 kernel/jump_label.c:149
 static_key_slow_dec+0x51/0x90 kernel/jump_label.c:174
 net_disable_timestamp+0x3b/0x50 net/core/dev.c:1728
 sock_disable_timestamp+0x98/0xc0 net/core/sock.c:403
 __sk_destruct+0x27d/0x6b0 net/core/sock.c:1441
 sk_destruct+0x47/0x80 net/core/sock.c:1460
 __sk_free+0x57/0x230 net/core/sock.c:1468
 sock_wfree+0xae/0x120 net/core/sock.c:1645
 skb_release_head_state+0xfc/0x200 net/core/skbuff.c:655
 skb_release_all+0x15/0x60 net/core/skbuff.c:668
 __kfree_skb+0x15/0x20 net/core/skbuff.c:684
 kfree_skb+0x16e/0x4c0 net/core/skbuff.c:705
 inet_frag_destroy+0x121/0x290 net/ipv4/inet_fragment.c:304
 inet_frag_put include/net/inet_frag.h:133 [inline]
 nf_ct_frag6_gather+0x1106/0x3840
net/ipv6/netfilter/nf_conntrack_reasm.c:617
 ipv6_defrag+0x1be/0x2b0 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c:68
 nf_hook_entry_hookfn include/linux/netfilter.h:102 [inline]
 nf_hook_slow+0xc3/0x290 net/netfilter/core.c:310
 nf_hook include/linux/netfilter.h:212 [inline]
 __ip6_local_out+0x489/0x840 net/ipv6/output_core.c:160
 ip6_local_out+0x2d/0x170 net/ipv6/output_core.c:170
 ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1722
 ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1742
 rawv6_push_pending_frames net/ipv6/raw.c:613 [inline]
 rawv6_sendmsg+0x2d1a/0x3ec0 net/ipv6/raw.c:927
 inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:744
 sock_sendmsg_nosec net/socket.c:635 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:645
 sock_write_iter+0x326/0x600 net/socket.c:848
 do_iter_readv_writev+0x2e3/0x5b0 fs/read_write.c:695
 do_readv_writev+0x42c/0x9b0 fs/read_write.c:872
 vfs_writev+0x87/0xc0 fs/read_write.c:911
 do_writev+0x110/0x2c0 fs/read_write.c:944
 SYSC_writev fs/read_write.c:1017 [inline]
 SyS_writev+0x27/0x30 fs/read_write.c:1014
 entry_SYSCALL_64_fastpath+0x1f/0xc2
RIP: 0033:0x445559
RSP: 002b:00007f6f46fceb58 EFLAGS: 00000292 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000445559
RDX: 0000000000000001 RSI: 0000000020f1eff0 RDI: 0000000000000005
RBP: 00000000006e19c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000700000
R13: 0000000020f59000 R14: 0000000000000015 R15: 0000000000020400
BUG: sleeping function called from invalid context at
kernel/locking/mutex.c:752
in_atomic(): 1, irqs_disabled(): 0, pid: 23111, name: syz-executor14
INFO: lockdep is turned off.
CPU: 2 PID: 23111 Comm: syz-executor14 Not tainted 4.10.0-rc5+ #192
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs
01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:15 [inline]
 dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
 ___might_sleep+0x47e/0x650 kernel/sched/core.c:7780
 __might_sleep+0x95/0x1a0 kernel/sched/core.c:7739
 mutex_lock_nested+0x24f/0x1730 kernel/locking/mutex.c:752
 atomic_dec_and_mutex_lock+0x119/0x160 kernel/locking/mutex.c:1060
 __static_key_slow_dec+0x7a/0x1e0 kernel/jump_label.c:149
 static_key_slow_dec+0x51/0x90 kernel/jump_label.c:174
 net_disable_timestamp+0x3b/0x50 net/core/dev.c:1728
 sock_disable_timestamp+0x98/0xc0 net/core/sock.c:403
 __sk_destruct+0x27d/0x6b0 net/core/sock.c:1441
 sk_destruct+0x47/0x80 net/core/sock.c:1460
 __sk_free+0x57/0x230 net/core/sock.c:1468
 sock_wfree+0xae/0x120 net/core/sock.c:1645
 skb_release_head_state+0xfc/0x200 net/core/skbuff.c:655
 skb_release_all+0x15/0x60 net/core/skbuff.c:668
 __kfree_skb+0x15/0x20 net/core/skbuff.c:684
 kfree_skb+0x16e/0x4c0 net/core/skbuff.c:705
 inet_frag_destroy+0x121/0x290 net/ipv4/inet_fragment.c:304
 inet_frag_put include/net/inet_frag.h:133 [inline]
 nf_ct_frag6_gather+0x1106/0x3840
net/ipv6/netfilter/nf_conntrack_reasm.c:617
 ipv6_defrag+0x1be/0x2b0 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c:68
 nf_hook_entry_hookfn include/linux/netfilter.h:102 [inline]
 nf_hook_slow+0xc3/0x290 net/netfilter/core.c:310
 nf_hook include/linux/netfilter.h:212 [inline]
 __ip6_local_out+0x489/0x840 net/ipv6/output_core.c:160
 ip6_local_out+0x2d/0x170 net/ipv6/output_core.c:170
 ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1722
 ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1742
 rawv6_push_pending_frames net/ipv6/raw.c:613 [inline]
 rawv6_sendmsg+0x2d1a/0x3ec0 net/ipv6/raw.c:927
 inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:744
 sock_sendmsg_nosec net/socket.c:635 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:645
 sock_write_iter+0x326/0x600 net/socket.c:848
 do_iter_readv_writev+0x2e3/0x5b0 fs/read_write.c:695
 do_readv_writev+0x42c/0x9b0 fs/read_write.c:872
 vfs_writev+0x87/0xc0 fs/read_write.c:911
 do_writev+0x110/0x2c0 fs/read_write.c:944
 SYSC_writev fs/read_write.c:1017 [inline]
 SyS_writev+0x27/0x30 fs/read_write.c:1014
 entry_SYSCALL_64_fastpath+0x1f/0xc2
RIP: 0033:0x445559

Fixes: b90e5794c5bd ("net: dont call jump_label_dec from irq context")
Suggested-by: Cong Wang <xiyou.wangcong@gmail.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>