From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C5EBF1EA8D; Mon, 12 Aug 2024 16:05:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723478755; cv=none; b=LRB77FLiRiMjTtin4RVoTXmIxTOJHDdHTJCMAyePFQCFgh2day/5jcvd97zb/4I9dFYs2mCbBH5iLc1kAK/7ECpDQ5Ju385k5009UObdrzULUbznWcRIdxk7niF3fdxKHxbfV38fW8j/9RDVF6vsNG+UHh+bKqOrfZweO788WCk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723478755; c=relaxed/simple; bh=8y37QS8atlPhWadaai0bDuooj1P8r3w62u1h85Qzht8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=txUpmGpzSjswuO7OVqgvJVmbvWl4Ks5eosc4sx75EUbtyTOLehshdjw5GrUdbPeNQs18cD1vLAarAU8xMkMJ17Veezf5VjqSEjmUj5DUDG2W1l93n4cIWPeA8b874KZ8ldO26HfkVTxRN0tPmktFXtt82ILbkANZt0NKY0+5MMc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sk4g+3lt; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sk4g+3lt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2AEAFC32782; Mon, 12 Aug 2024 16:05:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723478755; bh=8y37QS8atlPhWadaai0bDuooj1P8r3w62u1h85Qzht8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sk4g+3lt6h6uMn3f9bg+HDLj9cU2tbBoB+4nCVs534z1O9iyTHXCTkjMLCq8G5lB2 SH450RDC5dXnVthoEo0nixrDc6QncGYVfRJ/XSuObTPFYHZYBhi0H+v2/NkoM7h6dF J/pBMnmItDxxbj/4dK3c55LNBdtnIS1y61ux1tx0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+263426984509be19c9a0@syzkaller.appspotmail.com, Nikolay Aleksandrov , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1 009/150] net: bridge: mcast: wait for previous gc cycles when removing port Date: Mon, 12 Aug 2024 18:01:30 +0200 Message-ID: <20240812160125.513197249@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240812160125.139701076@linuxfoundation.org> References: <20240812160125.139701076@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org 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: Nikolay Aleksandrov [ Upstream commit 92c4ee25208d0f35dafc3213cdf355fbe449e078 ] syzbot hit a use-after-free[1] which is caused because the bridge doesn't make sure that all previous garbage has been collected when removing a port. What happens is: CPU 1 CPU 2 start gc cycle remove port acquire gc lock first wait for lock call br_multicasg_gc() directly acquire lock now but free port the port can be freed while grp timers still running Make sure all previous gc cycles have finished by using flush_work before freeing the port. [1] BUG: KASAN: slab-use-after-free in br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861 Read of size 8 at addr ffff888071d6d000 by task syz.5.1232/9699 CPU: 1 PID: 9699 Comm: syz.5.1232 Not tainted 6.10.0-rc5-syzkaller-00021-g24ca36a562d6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0xc3/0x620 mm/kasan/report.c:488 kasan_report+0xd9/0x110 mm/kasan/report.c:601 br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861 call_timer_fn+0x1a3/0x610 kernel/time/timer.c:1792 expire_timers kernel/time/timer.c:1843 [inline] __run_timers+0x74b/0xaf0 kernel/time/timer.c:2417 __run_timer_base kernel/time/timer.c:2428 [inline] __run_timer_base kernel/time/timer.c:2421 [inline] run_timer_base+0x111/0x190 kernel/time/timer.c:2437 Reported-by: syzbot+263426984509be19c9a0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=263426984509be19c9a0 Fixes: e12cec65b554 ("net: bridge: mcast: destroy all entries via gc") Signed-off-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20240802080730.3206303-1-razor@blackwall.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/bridge/br_multicast.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 9765f9f9bf7ff..3cd2b648408d6 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1890,16 +1890,14 @@ void br_multicast_del_port(struct net_bridge_port *port) { struct net_bridge *br = port->br; struct net_bridge_port_group *pg; - HLIST_HEAD(deleted_head); struct hlist_node *n; /* Take care of the remaining groups, only perm ones should be left */ spin_lock_bh(&br->multicast_lock); hlist_for_each_entry_safe(pg, n, &port->mglist, mglist) br_multicast_find_del_pg(br, pg); - hlist_move_list(&br->mcast_gc_list, &deleted_head); spin_unlock_bh(&br->multicast_lock); - br_multicast_gc(&deleted_head); + flush_work(&br->mcast_gc_work); br_multicast_port_ctx_deinit(&port->multicast_ctx); free_percpu(port->mcast_stats); } -- 2.43.0