From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A951B4A9D65 for ; Wed, 30 Sep 2026 12:30:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790771412; cv=none; b=DG6bAVJ1BAK8Nv0qMuTZJqegSQ3AELN6T3xm/Qb4+SXYbx9FiyfPMInkmrTuFFBwdJvg5VjQVC60J5iTqLFmZPGrxirpBa4tETZIsNii904qgXvUXsqP5RfC//m/ck14R3ydUVbVAL0gIkRDkM8XF/LjDKkq8JmFi5PHQz0poJw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790771412; c=relaxed/simple; bh=JJpYWCHBcf+0Oio2PaA0hFPHL2ZrOuREv6f1YnazJ7E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WIBn6lx05iukQ/1LOQvmSlPaIMtDzO0s8Un8qj2oBLGSBzV9PLdv719yjMHHp1G599Ot/o7U7oCNRFkJ1qSPAlhPHOevFwZn5YtZ6xjuNRMxn/teMiErO1SJIOaW261L0+CzwgaMXsN+4FefjJhEixfCx+oNweUG12trCOHMibo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aAr2pxss; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aAr2pxss" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB6E91F000FF; Wed, 30 Sep 2026 12:30:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790771411; bh=gssdwueZdfWJa4GUMTZC8LCY1EZRe/GvkHiIcWjIwxM=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=aAr2pxssQ+CvsJnHuR9Wr3kD7wuKtzqe5t9uanVRNIp9dfxaA5o6QzxZTFDpsG73w gqZ0nEL+JIXN3CbqdSnjuOj3dGfmRLG4Ruc0nfsNwj5Bqbu2lrDf25gpwrcxfeYU0F d6N08cq3wX1fOg+nbxF4S6AN8wZE8wxdSxQPlQy5ZRQxFPJ6XvZVFnpXXs1ujsPxyL 6vpwSSkmmVFqPpyZsYAS4GAdOMpGXr0L+nPiVq/sPSTl7lnkieALUy8x6X87d9l4OG QLFs22b9WTv7aLNVWADOYDPKGkErOzjrX2uszdwPlqUh8WLTiLo5Vg3tPipq7c+Kr1 zg+fFbxBINKRA== Message-ID: <855537d4-5c35-4bcb-aa58-82aa981e46fc@kernel.org> Date: Wed, 30 Sep 2026 06:30:10 -0600 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net 1/2] ipv4: fix IP ID reuse in ip_select_ident_segs() Content-Language: en-US To: Eric Dumazet , "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Willem de Bruijn , Ido Schimmel , netdev@vger.kernel.org, edumazet@google.com References: <20260929131247.401104-1-edumazet@kernel.org> <20260929131247.401104-2-edumazet@kernel.org> From: David Ahern In-Reply-To: <20260929131247.401104-2-edumazet@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/29/26 8:12 AM, 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, see > following patch in this series). > > Use atomic_fetch_add() instead, like the TCP path. > > Fixes: f866fbc842de ("ipv4: fix data-races around inet->inet_id") > Signed-off-by: Eric Dumazet > --- > include/net/ip.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > Reviewed-by: David Ahern