From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Eric Dumazet <edumazet@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>,
David Ahern <dsahern@kernel.org>,
Ido Schimmel <idosch@nvidia.com>,
netdev@vger.kernel.org, edumazet@google.com,
Eric Dumazet <edumazet@kernel.org>,
Jiayuan Chen <jiayuan.chen@linux.dev>
Subject: Re: [PATCH v2 net 1/2] ipv4: fix IP ID reuse in ip_select_ident_segs()
Date: Wed, 30 Sep 2026 11:11:55 -0400 [thread overview]
Message-ID: <willemdebruijn.kernel.39a4c29511f@gmail.com> (raw)
In-Reply-To: <20260930144018.1174068-2-edumazet@kernel.org>
Eric Dumazet wrote:
> ip_select_ident_segs() must put the first of the @segs reserved IP IDs
> in iph->id, as GSO assigns id, id + 1, ..., id + segs - 1 to segments.
>
> Commit f866fbc842de ("ipv4: fix data-races around inet->inet_id")
> used atomic_add_return() for non-TCP sockets, which returns the first
> ID of the next packet instead. Consecutive GSO packets can then reuse
> IP IDs.
>
> SCTP GSO is affected. Other callers use segs == 1, and only see
> a harmless off-by-one (UDP GSO has a separate, older issue).
>
> Use atomic_fetch_add() instead, like the TCP path.
>
> Fixes: f866fbc842de ("ipv4: fix data-races around inet->inet_id")
> Signed-off-by: Eric Dumazet <edumazet@kernel.org>
> Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
> Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
next prev parent reply other threads:[~2026-09-30 15:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-30 14:40 [PATCH v2 net 0/2] ipv4: fix IP ID reuse for GSO packets Eric Dumazet
2026-09-30 14:40 ` [PATCH v2 net 1/2] ipv4: fix IP ID reuse in ip_select_ident_segs() Eric Dumazet
2026-09-30 15:11 ` Willem de Bruijn [this message]
2026-09-30 14:40 ` [PATCH v2 net 2/2] ipv4: reserve one IP ID per segment for UDP GSO packets Eric Dumazet
2026-09-30 15:12 ` Willem de Bruijn
2026-10-05 22:10 ` [PATCH v2 net 0/2] ipv4: fix IP ID reuse for " patchwork-bot+netdevbpf
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