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 CC7304FDE69 for ; Mon, 7 Sep 2026 15:01:08 +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=1788793271; cv=none; b=UmOmSmc+CYU1LZ7CtFTrXQtZt4xC6OIxpvEwSXjQLqipba7VEbfhaYEQHjEfap6BkwjEqrq7B4cPeQ76gMnVW+IVbLRP+Zm+zLVfweqKN3NwUd0dixa6qE4yTdB+5ueqaoGERH5a2K5aVNAWQeM5dJaj1AoMk7CF4lWy6MfyOyg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788793271; c=relaxed/simple; bh=cCHH/WcMLePT4CzQs0qe+orKA6zQJvaQ4a848ibTyb0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=I+1wbv6O8lcz03m67sW8Ej6JzxxwMBHO2MO4wuo+Jf4oWlG6lgn+M82rpGjEZGDVA0fxIGrGf53YyfGTchx7vAKrxl7Ajcdcw/ww1+Gtr4Rz5Fd/YsngxyRtiBNg9ZttxC7yxAPJemtlHLss/93wsGASJjBiawkCAZSd+Xoq0L8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hudPfjJ0; 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="hudPfjJ0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C40611F00A3A; Mon, 7 Sep 2026 15:01:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788793267; bh=4ayJfwfjeNi/BPXvY4xEX8x3AUb9Jjhc6mj7RqBVwBc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hudPfjJ09FGn3ojvX2BtE8SGlvT12Sz9ee2ooOo8IbclPuOCRpxMxYijbei6VfE3s jU763ydizKvXvndKVeP84T/rgsye4cF6/OtoKZcfxgTeGYcI+WaMpM7VJaObhnwFJF abcQS39oyBOC4JDLwYoV6EU9dXLiwkMkAcnOV8IeGZg1puAPihNHtzVx4so3HxhWzU xnl5u1OlA6vqHON+fym840xMd/FZhmmp4lCOPp2wGKhF7hgqpjvCArTQKXgnvzaHrk n+6+2HPeE1tui86UWCwlr2FvW1THFlCv87TbH4OYiie4BUUCOrBQD2i/E53Og7YGW5 sp2M+DogCa91w== From: Sasha Levin To: stable@vger.kernel.org Cc: Frank Sorenson , Namjae Jeon , Paulo Alcantara , Sasha Levin Subject: [PATCH 6.12.y 6/6] smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 Date: Mon, 7 Sep 2026 11:00:59 -0400 Message-ID: <20260907150059.3712249-6-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260907150059.3712249-1-sashal@kernel.org> References: <2026090303-ashamed-silver-ed5c@gregkh> <20260907150059.3712249-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Frank Sorenson [ Upstream commit 730d0bb19507b9e19c2fe5343109ac618e2fbce5 ] When a valid primary TRANSACT2 response has been received (mid->resp_buf set, mid->multiRsp true) and a subsequent secondary response causes cifs_check_trans2() to return false -- either because the SMB header is invalid (malformed != 0) or because check2ndT2() rejects the PDU -- handle_mid() overwrites mid->resp_buf with the new buffer (leaking the primary buffer) and, because mid->multiRsp is set, skips the server->smallbuf/bigbuf NULL-out. When the user thread frees mid->resp_buf, server->smallbuf or server->bigbuf is left dangling; the demux thread reuses it for the next packet, resulting in a use-after-free. Combine both early-exit conditions and, when mid->multiRsp is already set, abort the pending transaction inline: set multiEnd, call dequeue_mid() with malformed=true, and return true so handle_mid() exits without touching mid->resp_buf or the server buffer pointers. Fixes: 316cf94a910f ("CIFS: Move trans2 processing to ops struct") Cc: stable@vger.kernel.org # cifs_check_trans2() is in smb1ops.c on kernels < 7.0 Signed-off-by: Frank Sorenson Signed-off-by: Namjae Jeon Signed-off-by: Paulo Alcantara Signed-off-by: Sasha Levin --- fs/smb/client/smb1transport.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/fs/smb/client/smb1transport.c b/fs/smb/client/smb1transport.c index 8e66a2d21f406..081885c222a9c 100644 --- a/fs/smb/client/smb1transport.c +++ b/fs/smb/client/smb1transport.c @@ -157,10 +157,18 @@ bool cifs_check_trans2(struct mid_q_entry *mid, struct TCP_Server_Info *server, char *buf, int malformed) { - if (malformed) - return false; - if (check2ndT2(buf) <= 0) + if (malformed || check2ndT2(buf) <= 0) { + /* mid->multiRsp blocks the server buf detach in handle_mid(); + * returning false here would leak resp_buf and leave a dangling + * server->smallbuf/bigbuf after the user thread frees resp_buf. + */ + if (mid->multiRsp) { + mid->multiEnd = true; + dequeue_mid(server, mid, true); + return true; + } return false; + } mid->multiRsp = true; if (mid->resp_buf) { /* merge response - fix up 1st*/ -- 2.53.0