linux-toradex.git/crypto/api.c, branch v3.10.2

crypto: algboss - Hold ref count on larval

2013-06-25T11:15:17+00:00

On Thu, Jun 20, 2013 at 10:00:21AM +0200, Daniel Borkmann wrote:
> After having fixed a NULL pointer dereference in SCTP 1abd165e ("net:
> sctp: fix NULL pointer dereference in socket destruction"), I ran into
> the following NULL pointer dereference in the crypto subsystem with
> the same reproducer, easily hit each time:
> 
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [] __wake_up_common+0x31/0x90
> PGD 0
> Oops: 0000 [#1] SMP
> Modules linked in: padlock_sha(F-) sha256_generic(F) sctp(F) libcrc32c(F) [..]
> CPU: 6 PID: 3326 Comm: cryptomgr_probe Tainted: GF            3.10.0-rc5+ #1
> Hardware name: Dell Inc. PowerEdge T410/0H19HD, BIOS 1.6.3 02/01/2011
> task: ffff88007b6cf4e0 ti: ffff88007b7cc000 task.ti: ffff88007b7cc000
> RIP: 0010:[]  [] __wake_up_common+0x31/0x90
> RSP: 0018:ffff88007b7cde08  EFLAGS: 00010082
> RAX: ffffffffffffffe8 RBX: ffff88003756c130 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffff88003756c130
> RBP: ffff88007b7cde48 R08: 0000000000000000 R09: ffff88012b173200
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000282
> R13: ffff88003756c138 R14: 0000000000000000 R15: 0000000000000000
> FS:  0000000000000000(0000) GS:ffff88012fc60000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: 0000000000000000 CR3: 0000000001a0b000 CR4: 00000000000007e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Stack:
>  ffff88007b7cde28 0000000300000000 ffff88007b7cde28 ffff88003756c130
>  0000000000000282 ffff88003756c128 ffffffff81227670 0000000000000000
>  ffff88007b7cde78 ffffffff810722b7 ffff88007cdcf000 ffffffff81a90540
> Call Trace:
>  [] ? crypto_alloc_pcomp+0x20/0x20
>  [] complete_all+0x47/0x60
>  [] cryptomgr_probe+0x98/0xc0
>  [] ? crypto_alloc_pcomp+0x20/0x20
>  [] kthread+0xce/0xe0
>  [] ? kthread_freezable_should_stop+0x70/0x70
>  [] ret_from_fork+0x7c/0xb0
>  [] ? kthread_freezable_should_stop+0x70/0x70
> Code: 41 56 41 55 41 54 53 48 83 ec 18 66 66 66 66 90 89 75 cc 89 55 c8
>       4c 8d 6f 08 48 8b 57 08 41 89 cf 4d 89 c6 48 8d 42 e
> RIP  [] __wake_up_common+0x31/0x90
>  RSP 
> CR2: 0000000000000000
> ---[ end trace b495b19270a4d37e ]---
> 
> My assumption is that the following is happening: the minimal SCTP
> tool runs under ``echo 1 > /proc/sys/net/sctp/auth_enable'', hence
> it's making use of crypto_alloc_hash() via sctp_auth_init_hmacs().
> It forks itself, heavily allocates, binds, listens and waits in
> accept on sctp sockets, and then randomly kills some of them (no
> need for an actual client in this case to hit this). Then, again,
> allocating, binding, etc, and then killing child processes.
> 
> The problem that might be happening here is that cryptomgr requests
> the module to probe/load through cryptomgr_schedule_probe(), but
> before the thread handler cryptomgr_probe() returns, we return from
> the wait_for_completion_interruptible() function and probably already
> have cleared up larval, thus we run into a NULL pointer dereference
> when in cryptomgr_probe() complete_all() is being called.
> 
> If we wait with wait_for_completion() instead, this panic will not
> occur anymore. This is valid, because in case a signal is pending,
> cryptomgr_probe() returns from probing anyway with properly calling
> complete_all().

The use of wait_for_completion_interruptible is intentional so that
we don't lock up the thread if a bug causes us to never wake up.

This bug is caused by the helper thread using the larval without
holding a reference count on it.  If the helper thread completes
after the original thread requesting for help has gone away and
destroyed the larval, then we get the crash above.

So the fix is to hold a reference count on the larval.

Cc:  # 3.6+
Reported-by: Daniel Borkmann 
Tested-by: Daniel Borkmann 
Signed-off-by: Herbert Xu

crypto: api - Fix checkpatch errors

2010-02-16T12:26:46+00:00

Signed-off-by: Richard Hartmann 
Signed-off-by: Herbert Xu

crypto: api - Remove frontend argument from extsize/init_tfm

2009-07-14T04:58:15+00:00

As the extsize and init_tfm functions belong to the frontend the
frontend argument is superfluous.

Signed-off-by: Herbert Xu

crypto: hash - Remove legacy hash/digest implementaion

2009-07-14T04:58:07+00:00

This patch removes the implementation of hash and digest now that
no algorithms use them anymore.  The interface though will remain
until the users are converted across.

Signed-off-by: Herbert Xu

crypto: api - Add crypto_attr_alg2 helper

2009-07-08T10:58:29+00:00

This patch adds the helper crypto_attr_alg2 which is similar to
crypto_attr_alg but takes an extra frontend argument.  This is
intended to be used by new style algorithm types such as shash.

Signed-off-by: Herbert Xu

crypto: api - Use formatting of module name

2009-06-02T04:13:14+00:00

Besdies, for the old code, gcc-4.3.3 produced this warning:
  "format not a string literal and no format arguments"

Signed-off-by: Alex Riesen 
Signed-off-by: Herbert Xu

crypto: api - Use kzfree

2009-06-02T04:04:11+00:00

Use kzfree() instead of memset() + kfree().

Signed-off-by: Johannes Weiner 
Reviewed-by: Pekka Enberg 
Signed-off-by: Andrew Morton 
Signed-off-by: Herbert Xu

crypto: api - Fix algorithm module auto-loading

2009-04-21T05:27:16+00:00

The commit a760a6656e6f00bb0144a42a048cf0266646e22c (crypto:
api - Fix module load deadlock with fallback algorithms) broke
the auto-loading of algorithms that require fallbacks.  The
problem is that the fallback mask check is missing an and which
cauess bits that should be considered to interfere with the
result.

Reported-by: Chuck Ebbert 
Signed-off-by: Herbert Xu

Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

2009-03-26T18:04:34+00:00

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (29 commits)
  crypto: sha512-s390 - Add missing block size
  hwrng: timeriomem - Breaks an allyesconfig build on s390:
  nlattr: Fix build error with NET off
  crypto: testmgr - add zlib test
  crypto: zlib - New zlib crypto module, using pcomp
  crypto: testmgr - Add support for the pcomp interface
  crypto: compress - Add pcomp interface
  netlink: Move netlink attribute parsing support to lib
  crypto: Fix dead links
  hwrng: timeriomem - New driver
  crypto: chainiv - Use kcrypto_wq instead of keventd_wq
  crypto: cryptd - Per-CPU thread implementation based on kcrypto_wq
  crypto: api - Use dedicated workqueue for crypto subsystem
  crypto: testmgr - Test skciphers with no IVs
  crypto: aead - Avoid infinite loop when nivaead fails selftest
  crypto: skcipher - Avoid infinite loop when cipher fails selftest
  crypto: api - Fix crypto_alloc_tfm/create_create_tfm return convention
  crypto: api - crypto_alg_mod_lookup either tested or untested
  crypto: amcc - Add crypt4xx driver
  crypto: ansi_cprng - Add maintainer
  ...

crypto: api - Fix module load deadlock with fallback algorithms

2009-02-26T06:06:31+00:00

With the mandatory algorithm testing at registration, we have
now created a deadlock with algorithms requiring fallbacks.
This can happen if the module containing the algorithm requiring
fallback is loaded first, without the fallback module being loaded
first.  The system will then try to test the new algorithm, find
that it needs to load a fallback, and then try to load that.

As both algorithms share the same module alias, it can attempt
to load the original algorithm again and block indefinitely.

As algorithms requiring fallbacks are a special case, we can fix
this by giving them a different module alias than the rest.  Then
it's just a matter of using the right aliases according to what
algorithms we're trying to find.

Signed-off-by: Herbert Xu