From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.manguebit.org (mx1.manguebit.org [143.255.12.172]) (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 1CD673264D4; Sat, 12 Sep 2026 15:20:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=143.255.12.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789226416; cv=none; b=hsUZL+9pMYzchLl/m6DBszoTDjoSMoEJ8LyIZimZDpYvYY23IvMClw8l5K1G7IUbIq+86zepxipzW/qOSYqql6oXYI7bUDazLdhg7LfLBpnss0IuqZf3cyv3VU7m5Tgt0yJg7ijYKUQW5ALxgAWHM8bUQSV4BT+rvewTPWUQSDc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789226416; c=relaxed/simple; bh=BrpOjzRvfMacMNezEnHboF2vo8DDz14l/uX51eIv46I=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=QcUzIAN+cdEDoG6mC8fRELYuz4Pruvp9uZMY6hK7UsWLO8zg9zVLvI2hmf+rjsp2mMa4wYPH4+5OmodtxB5rlfBNKr+Igr14YIl0MnwpeopeHPvcP/lMQ8xTxJA0uD4i6vYwqnKM+jpsPAieXx2lIdFuXgv5ipV2I9Dd2ud9Jvk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=manguebit.org; spf=pass smtp.mailfrom=manguebit.org; dkim=pass (2048-bit key) header.d=manguebit.org header.i=@manguebit.org header.b=7fpvNKw0; arc=none smtp.client-ip=143.255.12.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=manguebit.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=manguebit.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=manguebit.org header.i=@manguebit.org header.b="7fpvNKw0" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=manguebit.org; s=dkim; h=Content-Transfer-Encoding:MIME-Version:Message-ID: Date:Subject:Cc:To:From:Sender:Content-Type:Reply-To:Content-ID: Content-Description:In-Reply-To:References; bh=m+z8IGBcOx5mhev39atHGZpRwjVfvx6kUraHWgM4et8=; b=7fpvNKw012eTxZLyGANTiZIvvP /UazygCBsTu+1HagcvVyR8sPDyTAgqKQaE1cqN1ZuZkuPN8BCFVfP3BhQ1IXLeGzHRyXhmCOymvyJ SDKYyFLByMJjEi+9GyEKUs63LBJTbpcAQV/WM4k21r4agKf7BhFOIIEaMalHRELTUZbUKt1NVfwgQ yrIaLtBCJ1IqeET68ao7jjsRz3iXXy7UuBATWRi1UDCvtOJBNWXrjC3q49/OAQoIDYxLoLmPHaB/V 2YkvraXVSaICUGWRnJu4qIVe/O2QMky/sQKcdFn6kuSnn+B2oiCRuzRPNWQZIaw9+JbVDuDNTO2kv Jan0JIwQ==; Received: from pc by mx1.manguebit.org with local (Exim 4.99.5) id 1x5PWT-00000001Hhm-0HAg; Sat, 12 Sep 2026 12:20:09 -0300 From: Paulo Alcantara To: linux-cifs@vger.kernel.org Cc: syzbot+5003556314abc915a71f@syzkaller.appspotmail.com, David Howells , Shyam Prasad N , Ronnie Sahlberg , Tom Talpey , Bharath SM , Namjae Jeon , stable@vger.kernel.org Subject: [PATCH] smb: client: cancel reconnect work in clean_demultiplex_info() Date: Sat, 12 Sep 2026 12:20:08 -0300 Message-ID: <20260912152008.392251-1-pc@manguebit.org> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit clean_demultiplex_info() cancels server->echo delayed work but not server->reconnect, which can cause a use-after-free when the demultiplex thread exits while a reconnect work is still queued: cifs_demultiplex_thread() cifs_readv_from_socket() cifs_reconnect() __cifs_reconnect() cifs_queue_server_reconn() mod_delayed_work(cifsiod_wq, &server->reconnect, 0) clean_demultiplex_info() cancel_delayed_work_sync(&server->echo) // echo canceled // reconnect NOT canceled kfree_sensitive(server) // server freed ...later, on cifsiod_wq: smb2_reconnect_server() server->srv_count // UAF read of freed server Fix this by canceling server->reconnect delayed work in clean_demultiplex_info() before the server is freed, the same way cifs_put_tcp_session() already does. Reported-by: syzbot+5003556314abc915a71f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/r/6aa4a12d.f81106d8.2ab401.0023.GAE@google.com Fixes: 53e0e11efe92 ("CIFS: Fix a possible memory corruption during reconnect") Signed-off-by: Paulo Alcantara Cc: David Howells Cc: Shyam Prasad N Cc: Ronnie Sahlberg Cc: Tom Talpey Cc: Bharath SM Cc: Namjae Jeon Cc: stable@vger.kernel.org --- fs/smb/client/connect.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c index b6e98eb31673..bef710d9a3c3 100644 --- a/fs/smb/client/connect.c +++ b/fs/smb/client/connect.c @@ -1067,6 +1067,7 @@ clean_demultiplex_info(struct TCP_Server_Info *server) spin_unlock(&server->srv_lock); cancel_delayed_work_sync(&server->echo); + cancel_delayed_work_sync(&server->reconnect); spin_lock(&server->srv_lock); server->tcpStatus = CifsExiting; -- 2.55.0