Re: [PATCH] net/ipv4: Fix circular deadlock in do_ip_setsockop

[Eric Dumazet]

On Wed, Sep 18, 2024 at 1:51 AM AnantaSrikar <srikarananta01@xxxxxxxxx> wrote:
>
> Fixed the circular lock dependency reported by syzkaller.
>
> Signed-off-by: AnantaSrikar <srikarananta01@xxxxxxxxx>
> Reported-by: syzbot+e4c27043b9315839452d@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://syzkaller.appspot.com/bug?extid=e4c27043b9315839452d
> Fixes: d2bafcf224f3 ("Merge tag 'cgroup-for-6.11-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup")
> ---
>  net/ipv4/ip_sockglue.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index cf377377b52d..a8f46d1ba62b 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -1073,9 +1073,11 @@ int do_ip_setsockopt(struct sock *sk, int level, int optname,
>         }
>
>         err = 0;
> +
> +       sockopt_lock_sock(sk);
> +
>         if (needs_rtnl)
>                 rtnl_lock();
> -       sockopt_lock_sock(sk);
>
>         switch (optname) {
>         case IP_OPTIONS:

I think you missed an earlier conversation about SMC being at fault here.

https://lore.kernel.org/netdev/CANn89iKcWmufo83xy-SwSrXYt6UpL2Pb+5pWuzyYjMva5F8bBQ@xxxxxxxxxxxxxx/