<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/net, branch v3.4.92</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>mac80211: drop spoofed packets in ad-hoc mode</title>
<updated>2014-06-07T23:02:15+00:00</updated>
<author>
<name>Felix Fietkau</name>
<email>nbd@openwrt.org</email>
</author>
<published>2013-09-17T09:15:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=40dccfb2259f13eed66993a0d9b153e0695c8504'/>
<id>40dccfb2259f13eed66993a0d9b153e0695c8504</id>
<content type='text'>
commit 6329b8d917adc077caa60c2447385554130853a3 upstream.

If an Ad-Hoc node receives packets with the Cell ID or its own MAC
address as source address, it hits a WARN_ON in sta_info_insert_check()
With many packets, this can massively spam the logs. One way that this
can easily happen is through having Cisco APs in the area with rouge AP
detection and countermeasures enabled.
Such Cisco APs will regularly send fake beacons, disassoc and deauth
packets that trigger these warnings.

To fix this issue, drop such spoofed packets early in the rx path.

Reported-by: Thomas Huehn &lt;thomas@net.t-labs.tu-berlin.de&gt;
Signed-off-by: Felix Fietkau &lt;nbd@openwrt.org&gt;
Signed-off-by: Johannes Berg &lt;johannes.berg@intel.com&gt;
[bwh: Backported to 3.2: use compare_ether_addr() instead of ether_addr_equal()]
Signed-off-by: Ben Hutchings &lt;ben@decadent.org.uk&gt;
Cc: Qiang Huang &lt;h.huangqiang@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 6329b8d917adc077caa60c2447385554130853a3 upstream.

If an Ad-Hoc node receives packets with the Cell ID or its own MAC
address as source address, it hits a WARN_ON in sta_info_insert_check()
With many packets, this can massively spam the logs. One way that this
can easily happen is through having Cisco APs in the area with rouge AP
detection and countermeasures enabled.
Such Cisco APs will regularly send fake beacons, disassoc and deauth
packets that trigger these warnings.

To fix this issue, drop such spoofed packets early in the rx path.

Reported-by: Thomas Huehn &lt;thomas@net.t-labs.tu-berlin.de&gt;
Signed-off-by: Felix Fietkau &lt;nbd@openwrt.org&gt;
Signed-off-by: Johannes Berg &lt;johannes.berg@intel.com&gt;
[bwh: Backported to 3.2: use compare_ether_addr() instead of ether_addr_equal()]
Signed-off-by: Ben Hutchings &lt;ben@decadent.org.uk&gt;
Cc: Qiang Huang &lt;h.huangqiang@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>cfg80211: check wdev-&gt;netdev in connection work</title>
<updated>2014-06-07T23:02:14+00:00</updated>
<author>
<name>Johannes Berg</name>
<email>johannes.berg@intel.com</email>
</author>
<published>2013-05-23T16:10:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=377929f225ac24146fda8c5401553e556872a705'/>
<id>377929f225ac24146fda8c5401553e556872a705</id>
<content type='text'>
commit c815797663b72e3ac1736f1886538152bc48e4af upstream.

If a P2P-Device is present and another virtual interface triggers
the connection work, the system crash because it tries to check
if the P2P-Device's netdev (which doesn't exist) is up. Skip any
wdevs that have no netdev to fix this.

Reported-by: YanBo &lt;dreamfly281@gmail.com&gt;
Signed-off-by: Johannes Berg &lt;johannes.berg@intel.com&gt;
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings &lt;ben@decadent.org.uk&gt;
Cc: Qiang Huang &lt;h.huangqiang@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit c815797663b72e3ac1736f1886538152bc48e4af upstream.

If a P2P-Device is present and another virtual interface triggers
the connection work, the system crash because it tries to check
if the P2P-Device's netdev (which doesn't exist) is up. Skip any
wdevs that have no netdev to fix this.

Reported-by: YanBo &lt;dreamfly281@gmail.com&gt;
Signed-off-by: Johannes Berg &lt;johannes.berg@intel.com&gt;
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings &lt;ben@decadent.org.uk&gt;
Cc: Qiang Huang &lt;h.huangqiang@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>mac80211: introduce IEEE80211_HW_TEARDOWN_AGGR_ON_BAR_FAIL</title>
<updated>2014-06-07T23:02:07+00:00</updated>
<author>
<name>Stanislaw Gruszka</name>
<email>sgruszka@redhat.com</email>
</author>
<published>2012-12-03T11:56:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3a2c0d4b76454fe93fa4a5042962cfd76a0a31e2'/>
<id>3a2c0d4b76454fe93fa4a5042962cfd76a0a31e2</id>
<content type='text'>
commit 5b632fe85ec82e5c43740b52e74c66df50a37db3 upstream.

Commit f0425beda4d404a6e751439b562100b902ba9c98 "mac80211: retry sending
failed BAR frames later instead of tearing down aggr" caused regression
on rt2x00 hardware (connection hangs). This regression was fixed by
commit be03d4a45c09ee5100d3aaaedd087f19bc20d01 "rt2x00: Don't let
mac80211 send a BAR when an AMPDU subframe fails". But the latter
commit caused yet another problem reported in
https://bugzilla.kernel.org/show_bug.cgi?id=42828#c22

After long discussion in this thread:
http://mid.gmane.org/20121018075615.GA18212@redhat.com
and testing various alternative solutions, which failed on one or other
setup, we have no other good fix for the issues like just revert both
mentioned earlier commits.

To do not affect other hardware which benefit from commit
f0425beda4d404a6e751439b562100b902ba9c98, instead of reverting it,
introduce flag that when used will restore mac80211 behaviour before
the commit.

Signed-off-by: Stanislaw Gruszka &lt;sgruszka@redhat.com&gt;
[replaced link with mid.gmane.org that has message-id]
Signed-off-by: Johannes Berg &lt;johannes.berg@intel.com&gt;
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings &lt;ben@decadent.org.uk&gt;
[hq: Backported to 3.4: adjust context]
Signed-off-by: Qiang Huang &lt;h.huangqiang@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 5b632fe85ec82e5c43740b52e74c66df50a37db3 upstream.

Commit f0425beda4d404a6e751439b562100b902ba9c98 "mac80211: retry sending
failed BAR frames later instead of tearing down aggr" caused regression
on rt2x00 hardware (connection hangs). This regression was fixed by
commit be03d4a45c09ee5100d3aaaedd087f19bc20d01 "rt2x00: Don't let
mac80211 send a BAR when an AMPDU subframe fails". But the latter
commit caused yet another problem reported in
https://bugzilla.kernel.org/show_bug.cgi?id=42828#c22

After long discussion in this thread:
http://mid.gmane.org/20121018075615.GA18212@redhat.com
and testing various alternative solutions, which failed on one or other
setup, we have no other good fix for the issues like just revert both
mentioned earlier commits.

To do not affect other hardware which benefit from commit
f0425beda4d404a6e751439b562100b902ba9c98, instead of reverting it,
introduce flag that when used will restore mac80211 behaviour before
the commit.

Signed-off-by: Stanislaw Gruszka &lt;sgruszka@redhat.com&gt;
[replaced link with mid.gmane.org that has message-id]
Signed-off-by: Johannes Berg &lt;johannes.berg@intel.com&gt;
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings &lt;ben@decadent.org.uk&gt;
[hq: Backported to 3.4: adjust context]
Signed-off-by: Qiang Huang &lt;h.huangqiang@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net-gro: reset skb-&gt;truesize in napi_reuse_skb()</title>
<updated>2014-06-07T23:02:00+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2014-04-03T16:28:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d16beab575e17e46a4b187fb9f8211fab3adfbae'/>
<id>d16beab575e17e46a4b187fb9f8211fab3adfbae</id>
<content type='text'>
[ Upstream commit e33d0ba8047b049c9262fdb1fcafb93cb52ceceb ]

Recycling skb always had been very tough...

This time it appears GRO layer can accumulate skb-&gt;truesize
adjustments made by drivers when they attach a fragment to skb.

skb_gro_receive() can only subtract from skb-&gt;truesize the used part
of a fragment.

I spotted this problem seeing TcpExtPruneCalled and
TcpExtTCPRcvCollapsed that were unexpected with a recent kernel, where
TCP receive window should be sized properly to accept traffic coming
from a driver not overshooting skb-&gt;truesize.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit e33d0ba8047b049c9262fdb1fcafb93cb52ceceb ]

Recycling skb always had been very tough...

This time it appears GRO layer can accumulate skb-&gt;truesize
adjustments made by drivers when they attach a fragment to skb.

skb_gro_receive() can only subtract from skb-&gt;truesize the used part
of a fragment.

I spotted this problem seeing TcpExtPruneCalled and
TcpExtTCPRcvCollapsed that were unexpected with a recent kernel, where
TCP receive window should be sized properly to accept traffic coming
from a driver not overshooting skb-&gt;truesize.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>skb: Add inline helper for getting the skb end offset from head</title>
<updated>2014-06-07T23:02:00+00:00</updated>
<author>
<name>Alexander Duyck</name>
<email>alexander.h.duyck@intel.com</email>
</author>
<published>2012-05-04T14:26:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=1102122b2bdf4307cae269c725fab4c9c6141f5b'/>
<id>1102122b2bdf4307cae269c725fab4c9c6141f5b</id>
<content type='text'>
[ Upstream commit ec47ea82477404631d49b8e568c71826c9b663ac ]

With the recent changes for how we compute the skb truesize it occurs to me
we are probably going to have a lot of calls to skb_end_pointer -
skb-&gt;head.  Instead of running all over the place doing that it would make
more sense to just make it a separate inline skb_end_offset(skb) that way
we can return the correct value without having gcc having to do all the
optimization to cancel out skb-&gt;head - skb-&gt;head.

Signed-off-by: Alexander Duyck &lt;alexander.h.duyck@intel.com&gt;
Acked-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit ec47ea82477404631d49b8e568c71826c9b663ac ]

With the recent changes for how we compute the skb truesize it occurs to me
we are probably going to have a lot of calls to skb_end_pointer -
skb-&gt;head.  Instead of running all over the place doing that it would make
more sense to just make it a separate inline skb_end_offset(skb) that way
we can return the correct value without having gcc having to do all the
optimization to cancel out skb-&gt;head - skb-&gt;head.

Signed-off-by: Alexander Duyck &lt;alexander.h.duyck@intel.com&gt;
Acked-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ipv4: initialise the itag variable in __mkroute_input</title>
<updated>2014-06-07T23:02:00+00:00</updated>
<author>
<name>Li RongQing</name>
<email>roy.qing.li@gmail.com</email>
</author>
<published>2014-05-22T08:36:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=62e1a647e74f708eeabf1c79f3d40833d8ce45eb'/>
<id>62e1a647e74f708eeabf1c79f3d40833d8ce45eb</id>
<content type='text'>
[ Upstream commit fbdc0ad095c0a299e9abf5d8ac8f58374951149a ]

the value of itag is a random value from stack, and may not be initiated by
fib_validate_source, which called fib_combine_itag if CONFIG_IP_ROUTE_CLASSID
is not set

This will make the cached dst uncertainty

Signed-off-by: Li RongQing &lt;roy.qing.li@gmail.com&gt;
Acked-by: Alexei Starovoitov &lt;ast@plumgrid.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit fbdc0ad095c0a299e9abf5d8ac8f58374951149a ]

the value of itag is a random value from stack, and may not be initiated by
fib_validate_source, which called fib_combine_itag if CONFIG_IP_ROUTE_CLASSID
is not set

This will make the cached dst uncertainty

Signed-off-by: Li RongQing &lt;roy.qing.li@gmail.com&gt;
Acked-by: Alexei Starovoitov &lt;ast@plumgrid.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>act_mirred: do not drop packets when fails to mirror it</title>
<updated>2014-06-07T23:02:00+00:00</updated>
<author>
<name>Jason Wang</name>
<email>jasowang@redhat.com</email>
</author>
<published>2012-08-15T20:44:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=7c8a60a9e3cdfcc04bc4de488876c07225fa0347'/>
<id>7c8a60a9e3cdfcc04bc4de488876c07225fa0347</id>
<content type='text'>
[ Upstream commit 16c0b164bd24d44db137693a36b428ba28970c62 ]

We drop packet unconditionally when we fail to mirror it. This is not intended
in some cases. Consdier for kvm guest, we may mirror the traffic of the bridge
to a tap device used by a VM. When kernel fails to mirror the packet in
conditions such as when qemu crashes or stop polling the tap, it's hard for the
management software to detect such condition and clean the the mirroring
before. This would lead all packets to the bridge to be dropped and break the
netowrk of other virtual machines.

To solve the issue, the patch does not drop packets when kernel fails to mirror
it, and only drop the redirected packets.

Signed-off-by: Jason Wang &lt;jasowang@redhat.com&gt;
Signed-off-by: Jamal Hadi Salim &lt;jhs@mojatatu.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 16c0b164bd24d44db137693a36b428ba28970c62 ]

We drop packet unconditionally when we fail to mirror it. This is not intended
in some cases. Consdier for kvm guest, we may mirror the traffic of the bridge
to a tap device used by a VM. When kernel fails to mirror the packet in
conditions such as when qemu crashes or stop polling the tap, it's hard for the
management software to detect such condition and clean the the mirroring
before. This would lead all packets to the bridge to be dropped and break the
netowrk of other virtual machines.

To solve the issue, the patch does not drop packets when kernel fails to mirror
it, and only drop the redirected packets.

Signed-off-by: Jason Wang &lt;jasowang@redhat.com&gt;
Signed-off-by: Jamal Hadi Salim &lt;jhs@mojatatu.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ipv4: fib_semantics: increment fib_info_cnt after fib_info allocation</title>
<updated>2014-06-07T23:01:59+00:00</updated>
<author>
<name>Sergey Popovich</name>
<email>popovich_sergei@mail.ru</email>
</author>
<published>2014-05-06T15:23:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=dfe37ad5ddd74bfb299bb50b62db2f5c6b0bc78a'/>
<id>dfe37ad5ddd74bfb299bb50b62db2f5c6b0bc78a</id>
<content type='text'>
[ Upstream commit aeefa1ecfc799b0ea2c4979617f14cecd5cccbfd ]

Increment fib_info_cnt in fib_create_info() right after successfuly
alllocating fib_info structure, overwise fib_metrics allocation failure
leads to fib_info_cnt incorrectly decremented in free_fib_info(), called
on error path from fib_create_info().

Signed-off-by: Sergey Popovich &lt;popovich_sergei@mail.ru&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit aeefa1ecfc799b0ea2c4979617f14cecd5cccbfd ]

Increment fib_info_cnt in fib_create_info() right after successfuly
alllocating fib_info structure, overwise fib_metrics allocation failure
leads to fib_info_cnt incorrectly decremented in free_fib_info(), called
on error path from fib_create_info().

Signed-off-by: Sergey Popovich &lt;popovich_sergei@mail.ru&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: ipv4: ip_forward: fix inverted local_df test</title>
<updated>2014-06-07T23:01:59+00:00</updated>
<author>
<name>Florian Westphal</name>
<email>fw@strlen.de</email>
</author>
<published>2014-05-04T21:24:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=bd91cb56f951a7b0da8c3098ea9cd56854ece66c'/>
<id>bd91cb56f951a7b0da8c3098ea9cd56854ece66c</id>
<content type='text'>
[ Upstream commit ca6c5d4ad216d5942ae544bbf02503041bd802aa ]

local_df means 'ignore DF bit if set', so if its set we're
allowed to perform ip fragmentation.

This wasn't noticed earlier because the output path also drops such skbs
(and emits needed icmp error) and because netfilter ip defrag did not
set local_df until couple of days ago.

Only difference is that DF-packets-larger-than MTU now discarded
earlier (f.e. we avoid pointless netfilter postrouting trip).

While at it, drop the repeated test ip_exceeds_mtu, checking it once
is enough...

Fixes: fe6cc55f3a9 ("net: ip, ipv6: handle gso skbs in forwarding path")
Signed-off-by: Florian Westphal &lt;fw@strlen.de&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit ca6c5d4ad216d5942ae544bbf02503041bd802aa ]

local_df means 'ignore DF bit if set', so if its set we're
allowed to perform ip fragmentation.

This wasn't noticed earlier because the output path also drops such skbs
(and emits needed icmp error) and because netfilter ip defrag did not
set local_df until couple of days ago.

Only difference is that DF-packets-larger-than MTU now discarded
earlier (f.e. we avoid pointless netfilter postrouting trip).

While at it, drop the repeated test ip_exceeds_mtu, checking it once
is enough...

Fixes: fe6cc55f3a9 ("net: ip, ipv6: handle gso skbs in forwarding path")
Signed-off-by: Florian Westphal &lt;fw@strlen.de&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp_cubic: fix the range of delayed_ack</title>
<updated>2014-06-07T23:01:59+00:00</updated>
<author>
<name>Liu Yu</name>
<email>allanyuliu@tencent.com</email>
</author>
<published>2014-04-30T09:34:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=b8b4577dff4f2d0964546a6ee9dcb542b13c3337'/>
<id>b8b4577dff4f2d0964546a6ee9dcb542b13c3337</id>
<content type='text'>
[ Upstream commit 0cda345d1b2201dd15591b163e3c92bad5191745 ]

commit b9f47a3aaeab (tcp_cubic: limit delayed_ack ratio to prevent
divide error) try to prevent divide error, but there is still a little
chance that delayed_ack can reach zero. In case the param cnt get
negative value, then ratio+cnt would overflow and may happen to be zero.
As a result, min(ratio, ACK_RATIO_LIMIT) will calculate to be zero.

In some old kernels, such as 2.6.32, there is a bug that would
pass negative param, which then ultimately leads to this divide error.

commit 5b35e1e6e9c (tcp: fix tcp_trim_head() to adjust segment count
with skb MSS) fixed the negative param issue. However,
it's safe that we fix the range of delayed_ack as well,
to make sure we do not hit a divide by zero.

CC: Stephen Hemminger &lt;shemminger@vyatta.com&gt;
Signed-off-by: Liu Yu &lt;allanyuliu@tencent.com&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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<pre>
[ Upstream commit 0cda345d1b2201dd15591b163e3c92bad5191745 ]

commit b9f47a3aaeab (tcp_cubic: limit delayed_ack ratio to prevent
divide error) try to prevent divide error, but there is still a little
chance that delayed_ack can reach zero. In case the param cnt get
negative value, then ratio+cnt would overflow and may happen to be zero.
As a result, min(ratio, ACK_RATIO_LIMIT) will calculate to be zero.

In some old kernels, such as 2.6.32, there is a bug that would
pass negative param, which then ultimately leads to this divide error.

commit 5b35e1e6e9c (tcp: fix tcp_trim_head() to adjust segment count
with skb MSS) fixed the negative param issue. However,
it's safe that we fix the range of delayed_ack as well,
to make sure we do not hit a divide by zero.

CC: Stephen Hemminger &lt;shemminger@vyatta.com&gt;
Signed-off-by: Liu Yu &lt;allanyuliu@tencent.com&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
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