ACK: [SRU][Bionic][PATCH 0/1] Fix WARN_ON in sk_stream_kill_queues

[Thadeu Lima de Souza Cascardo]

On Thu, Jun 15, 2023 at 09:00:18PM +0100, Andrei Gherzan wrote:
> BugLink: https://bugs.launchpad.net/bugs/2020279
> 
> [Impact]
> 
> The upstream commit 323fbd0edf3f ("net: dccp: Add handling of
> IPV6_PKTOPTIONS to dccp_v6_do_rcv()") started to trigger WARN_ON in
> sk_stream_kill_queues. Bionic doesn't have this commit but the same is
> triggered with ca43ccf41224b023fc290073d5603a755fd12eed ("dccp/tcp:
> Avoid negative sk_forward_alloc by ipv6_pinfo.pktoptions.") which is
> included in Bionic.
> 
> [Fix]
> 
> Upstream already has the fix merged and also backported in various versions
> including 4.14 from which the fix was cherry-picked for the Ubuntu
> Bionic tree.
> 
> [Test Plan]
> 
> The bug was reproduced, and the fix was validated with the program
> referenced in the patch's description:
> https://lore.kernel.org/netdev/20230208004245.83497-1-kuniyu@amazon.com/
> 
> [Where problems could occur]
> 
> The regression can be considered low, since this commit was backported
> on various versions from 4.14 to 6.2 (where the initial fix landed) and
> has been both reproduced and validated at runtime.
> 

I like how instead of having this section called "Potential regression", it
is titled "*Where* problems could occur" (emphasis mine). But in the body
of the section, you are stating "how likely" you think you may hit a
regression or why you think problems cannot occur, not *where* they would
likely occur. And by where I would like it to mean where in the code, which
subsystem, thinks like that.

I don't think we should dismiss the reasons why we think this unlikely will
cause a regression, but we can't keep ignoring the "where".

Acked-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>

> [Other Info]
> 
> All the Ubuntu kernel trees have been checked for this bug and only
> Bionic is affected. The earlier tree don't have the commits that trigger
> this bug while the later trees already include the fix.
> 
> Kuniyuki Iwashima (1):
>   net: Remove WARN_ON_ONCE(sk->sk_forward_alloc) from
>     sk_stream_kill_queues().
> 
>  net/caif/caif_socket.c | 1 +
>  net/core/stream.c      | 1 -
>  2 files changed, 1 insertion(+), 1 deletion(-)
> 
> -- 
> 2.34.1
> 
> 
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