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 BB0183FAE09 for ; Tue, 8 Sep 2026 12:20:06 +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=1788870008; cv=none; b=K6LC2R5M15A+ZpZQRL5ruAstx00a/vd6HtCzhuqa5Ols3rVI6NTH3Ijsuk9UjE2eT2N66qaSHrulB0T9o9k02MPg9rEcPfBIbBOhasSookl2zml96YlbP/DbSvfyJnodjlF/cuaRdPe40SF5jzh2O1T7C0DWK3jgXqILJQzZnwM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788870008; c=relaxed/simple; bh=U6eh6L63NuLw+kxHPSvSIbeatxPRnhJeO614g7Mmg4Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NHc9vpV0arhe/KigV5SZrNSZWDtB/sZOAIkE5THKe1DPsien0J8u55ykqiqByYX/nHDJqi+s+pE+GxB0KzQDso70fiInNepK9BSK2+X9uZ0NHJiWbmMjTSttNLJ4a0QWM8+BlYZuupHBGDr42k+mBuZzYcf1S0TVVqzg21MXaJU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2740C1F00A3E; Tue, 8 Sep 2026 12:20:04 +0000 (UTC) From: Sasha Levin To: stable@vger.kernel.org Cc: Frank Sorenson , Namjae Jeon , Paulo Alcantara , Sasha Levin Subject: [PATCH 5.10.y 3/3] smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 Date: Tue, 8 Sep 2026 08:20:00 -0400 Message-ID: <20260908122000.2049341-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260908122000.2049341-1-sashal@kernel.org> References: <2026090305-henchman-snipping-25aa@gregkh> <20260908122000.2049341-1-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 f2b19d7786f42..37b30d78a0883 100644 --- a/fs/smb/client/smb1transport.c +++ b/fs/smb/client/smb1transport.c @@ -152,10 +152,18 @@ 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