netdev - Re: [PATCH net-next] mptcp: pm: Fix undefined behavior in mptcp_remove_anno_list_by

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Message-ID: <20250325053058.412af7c5@kernel.org>
Date: Tue, 25 Mar 2025 05:30:58 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Thorsten Blum <thorsten.blum@...ux.dev>
Cc: Matthieu Baerts <matttbe@...nel.org>, Mat Martineau
 <martineau@...nel.org>, Geliang Tang <geliang@...nel.org>, "David S.
 Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo
 Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
 netdev@...r.kernel.org
Subject: Re: [PATCH net-next] mptcp: pm: Fix undefined behavior in
 mptcp_remove_anno_list_by_saddr()

On Tue, 25 Mar 2025 12:33:11 +0100 Thorsten Blum wrote:
> On 25. Mar 2025, at 12:06, Thorsten Blum wrote:
> > 
> > Commit e4c28e3d5c090 ("mptcp: pm: move generic PM helpers to pm.c")
> > removed a necessary if-check, leading to undefined behavior because
> > the freed pointer is subsequently returned from the function.
> > 
> > Reintroduce the if-check to fix this and add a local return variable to
> > prevent further checkpatch warnings, which originally led to the removal
> > of the if-check.
> > 
> > Fixes: e4c28e3d5c090 ("mptcp: pm: move generic PM helpers to pm.c")
> > Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
> > ---  
> 
> Never mind, technically it's not actually undefined behavior because of
> the implicit bool conversion, but returning a freed pointer still seems
> confusing.

CCing the list back in.
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