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 BD218471271; Tue, 21 Jul 2026 18:01:12 +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=1784656873; cv=none; b=h9I5HswT9ijWlmoI8u7stflFd+HyMbbaSQiLTHRMhmRVjJ4ylN+vx9neUO8J5y/R46pXZsca6+nP5mYLB93pSCnPTTcQ7EM/MTg5SNIzVSH76eZG3TsNjeuc97l1z7zDOe9wxMoTG2RLiSfX3EP25pmclhJjIBRLtLtELFStm+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784656873; c=relaxed/simple; bh=1ubtWrElNZ7DmGxSrqqaltd9x2niZrYYWBLMAjBPwtg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Zd2TfnPQut7nTAdYcuEkzuz1+8NtSFdPFpQDNHqxCeyzjs5+8enSxqaZdcpbtViF4lPVD56q3MpdjaemaD4KNLIUcaURZqCqYvugW1o5kMnc91jHVIIYQFMxY7KDQqWVtSzWc5EST0uTLDmdtNjBkJCXN0w0IeUXyhz8QPWvhnw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CvHp4yx5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CvHp4yx5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2EDF71F000E9; Tue, 21 Jul 2026 18:01:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784656872; bh=Bd1wRySnyY8mJespjUOwphZRChgrmqx734ws0wwaypk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CvHp4yx5E9934k2oVECHyAdehwAqpHjxg6+KnqceAXCZJHNlTGPm7olQAnoS71O6V iXPit4sBA9xpD7YdbWrK0Jb+/LsbATxpG1uxLmhuxx7DyzzSCO7oj1ku2GYKCb+fyO SmpoQvv3EmxlsPEaTgxBMsqSgUMkCJwpIhebFy34= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+64ec81389cbad56a8c35@syzkaller.appspotmail.com, Eric Dumazet , Jon Maloy , Tung Nguyen , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 0550/1611] tipc: fix UAF in tipc_l2_send_msg() Date: Tue, 21 Jul 2026 17:11:06 +0200 Message-ID: <20260721152527.748210657@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6 ] Syzbot reported a slab-use-after-free in ipvlan_hard_header() when called from tipc_l2_send_msg(). The root cause is that tipc_disable_l2_media() calls synchronize_net() while b->media_ptr is still valid. This allows concurrent RCU readers to obtain the device pointer after synchronize_net() has finished. The pointer is cleared later in bearer_disable(), but without any subsequent synchronization, allowing the device to be freed while still in use by readers. Fix this by clearing b->media_ptr in tipc_disable_l2_media() before calling synchronize_net(). This is safe to do now because the call order in bearer_disable() was reversed in 0d051bf93c06 ("tipc: make bearer packet filtering generic") to call tipc_node_delete_links() (which needs the pointer) before disable_media(). Fixes: 282b3a056225 ("tipc: send out RESET immediately when link goes down") https: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u Reported-by: syzbot+64ec81389cbad56a8c35@syzkaller.appspotmail.com Signed-off-by: Eric Dumazet Cc: Jon Maloy Reviewed-by: Tung Nguyen Link: https://patch.msgid.link/20260612135949.4010482-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/tipc/bearer.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c index ae1ddbf7185392..8866a3d713132c 100644 --- a/net/tipc/bearer.c +++ b/net/tipc/bearer.c @@ -482,6 +482,7 @@ void tipc_disable_l2_media(struct tipc_bearer *b) dev = (struct net_device *)rtnl_dereference(b->media_ptr); dev_remove_pack(&b->pt); RCU_INIT_POINTER(dev->tipc_ptr, NULL); + RCU_INIT_POINTER(b->media_ptr, NULL); synchronize_net(); dev_put(dev); } -- 2.53.0