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 5EECB44AB68; Tue, 21 Jul 2026 21:26:51 +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=1784669212; cv=none; b=p1ALyJ/LA91pKV9PlodL9gvgmelyVEhB9ufcM/xKDYbjcQ4gg0grTAfcjb9g9t9Z6ZHfJFE2XnzGTeTQomRE0WW4agwmlLzAHhJvS02IxYy/PK9SRwUAXphV3CBEfYXkAlwP6TmsI8LPaBTaF7a4oQP94p9Qh7u4D8WYwKF07CU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784669212; c=relaxed/simple; bh=YvyxuXOa0Di5wAL8ckl+3ZYqxNdsIbb6X3IgWGJNrKM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jx03S+WxZO5VYHDWyQWJvtGn9EseAP+BJotR2Ud5W3P8fhvdRkGVWv6g0YFBBzeKs0b7yo/6MqXS/IBzMXw4N5fUhNmtEVZ135d5HJNostIZjuhTofzC12AjZulY/spYGlu+zfjfqWIm4TzZAjConPc8j+trisQdW4ieeUDzusA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=qokvo0V4; 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="qokvo0V4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BDB621F000E9; Tue, 21 Jul 2026 21:26:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784669211; bh=4FBpcUMID+lwMs/FEZeUBSoTFtsMDgXrcXNTAo2pVVs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=qokvo0V4P5ExEjGLRNDRrnaxJvpuZQW6dnQuyB7d9JTUrEYaOgK+tFlyt2uO+k+Nd AbMyL31YoCLY9qpy0XSeK4Iyp/P8LQqY4F7+uWEaQO3YEnsiCh61Ed+AkQmXstD3/z ILG+IMy9d3kfo4bNtlwdsylz+KJb6XT7jEPqHtpo= 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 6.1 0467/1067] tipc: fix UAF in tipc_l2_send_msg() Date: Tue, 21 Jul 2026 17:17:48 +0200 Message-ID: <20260721152435.062090251@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152424.521567757@linuxfoundation.org> References: <20260721152424.521567757@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 6.1-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 538bb63e07d503..61b611450f208a 100644 --- a/net/tipc/bearer.c +++ b/net/tipc/bearer.c @@ -484,6 +484,7 @@ 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