Thread (11 messages) 11 messages, 4 authors, 2017-04-26

Re: net/tcp: warning in tcp_try_coalesce/skb_try_coalesce

From: Eric Dumazet <hidden>
Date: 2017-02-02 12:20:33
Also in: lkml

On Thu, 2017-02-02 at 10:05 +0100, Dmitry Vyukov wrote:
On Tue, Jan 31, 2017 at 3:27 PM, 'Eric Dumazet' via syzkaller
[off-list ref] wrote:
quoted
On Tue, Jan 31, 2017 at 5:17 AM, Andrey Konovalov [off-list ref] wrote:
quoted
Hi,

I've got the following error report while running the syzkaller fuzzer.

On commit 566cf877a1fcb6d6dc0126b076aad062054c2637 (4.10-rc6).

The fuzzer hits this issue quite often, but I don't have a working reproducer.

WARNING: CPU: 3 PID: 7091 at net/core/skbuff.c:4331
skb_try_coalesce+0x14b1/0x1f80 net/core/skbuff.c:4331
Kernel panic - not syncing: panic_on_warn set ...
...
quoted
Have you tried the patch we added recently into net-next ?

https://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=158f323b9868b59967ad96957c4ca388161be321

I've tried this patch, and it does _not_ help.
I am currently on a2ca3d617944417e9dd5f09fc8a4549cda115f4f, and I
applied the patch on top (had to do a little merging in af_netlink.c):
https://gist.githubusercontent.com/dvyukov/b4fd206f7dde763b3113a4543c57e7bb/raw/784c5b1bcb06f2a22c55eb4c4f8f83d627cd1ab9/gistfile1.txt
Still getting the same warning.

But now I have a repro:
https://gist.githubusercontent.com/dvyukov/88fdb6d93507b36f81377191b0694f9b/raw/81cc11e8b78b6bbc5cffc79b442ce998c49af226/gistfile1.txt
Interesting. This repro does not trigger the bug on net-next.
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