From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793925986; b=m4/mFfp+xqLxUm4yjTErUaKNGsgYIhCSgzosRCN/jDej1nTEdROGbtijJ1u752mATRHc cxGDxflaqYMpShHc2WGhO48l4nH69XTQ0gRIhqeUbwt+I2ldqK9Hd4GrPiauc8l514Lqu x1oKiJRWHvu/3QxMHodGswUBwXqOC5/q74Xion4++LjIHJ8O3bvFfFiGo117DEXVkjkbq ARr1KqrH8zZrTZtxdmBDXGK3Q/weoYQ19gKRRc1/vGuNtio3rReNLerbWR8+6R4tdlBAD vJzigHLwQh2Rqs/TnJ6QfIsGo6+uKfQErZvSWAafiblBew0RaX1JemrX7u0hoSD7C8Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793925986; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=ncUcAX0L7QUoA94f8Ey2Q/b0k77d+D+tUPYUCsJq/9I=; b=bfI6y8yQ5zPhWTggKxFP8VLwwP9RgLvvTq1lq5WaZRGxmXd1XFrL/Qz6uvfzx6xUhGXm oMnawejZfcJ9CzBCWZN7troSeCuZdGTfE0yc24NvurubBg75AsqaRj7pFF1wYN5BcEkGR N0fiBli/uFePcY0FhzpXXFRAg7zWpfJXv/Br+XDc9uGX5v5r+8F+vSC9m2vgMLAYf1xTh 6qF/ebtP5y2xQj0T5mKUG+UMNm7F+m6feYXf/dD917VUGi45JyNdhgU02ArTBOoM2Vy5H /dH85B4AhNx8a6iEV+wId5QC9UQ4UDscAIfUqjq8Q8kI+sKPYuKS2SxHy9UIMvBettg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=EKV8G3lA; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 10DC8606A31B for ; Fri, 6 Nov 2026 00:46:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=EKV8G3lA Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B9A41F0089F; Fri, 6 Nov 2026 00:46:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793925985; bh=ncUcAX0L7QUoA94f8Ey2Q/b0k77d+D+tUPYUCsJq/9I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EKV8G3lAVXiLyWQLkKsGee/Tx02QhljahCIFHWT0JekbV/7sPz/1wgHRsQ/s+sAmR 2StecOgAhVXOeCXmuTBffyCNr6r7gboU47Ti8ZqHTz63N3x5Ev1wDWkgO0LzhT5xmK VjLBtmRPqcdGAyl9FOv0PSX3nZMrnADhZlOxFkwIQOQpplKz5rYIX5ixfQ0+qtCaSZ Gkaf9jVjqZ1xUhhJ279JQ7/10CJx6WU1C+NiISM2pXyXCNqO6PNXIbACEyDrXrI2Ll jjDrn6rWry1R2VEyNylypJ3s/KM75AJoGH1flYr7qCsCYZUrlFLZIUSmJ+p94v77Ha idWRQAqnXiVdA== From: Sasha Levin To: stable@vger.kernel.org Cc: Abdifatah Suruur , Namjae Jeon , Paulo Alcantara , Sasha Levin Subject: [PATCH 5.15.y] smb: client: validate the data area in SMB2_read() Date: Thu, 5 Nov 2026 19:46:23 -0500 Message-ID: <20261106004456.3427593-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110422-kitty-unlocking-dd52@gregkh> References: <2026110422-kitty-unlocking-dd52@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Abdifatah Suruur [ Upstream commit 2ec9cdf469dd32bcf33073aeb30c08e9356e0ca1 ] SMB2_read() copies le32_to_cpu(rsp->DataLength) bytes from (char *)rsp + rsp->DataOffset without checking that the range lies within the response actually received. A READ response with DataOffset == 0 makes smb2_get_data_area_len() zero the data length, so smb2_check_message() accepts a frame as short as the fixed response, while SMB2_read() still uses the server-supplied DataLength, capped only by CIFS_MAX_MSGSIZE and the caller's length. A malicious server can answer the synchronous read used by the mfsymlinks (or SFU) symlink parser with an 81-byte READ response carrying DataOffset 0 and DataLength 1067, making the client copy 1067 bytes from a 448-byte receive object (KASAN slab-out-of-bounds; up to 16 KiB in the general case). Clamp a zero (or header-overlapping) DataOffset to read_rsp_size, as handle_read_data() does for the asynchronous path, and reject the response unless DataOffset + DataLength fits within rsp_iov.iov_len. The SMB1 helper was fixed the same way in 5be5bdda5863. Fixes: d8e050398d23 ("CIFS: Add readpage support for SMB2") Cc: stable@vger.kernel.org Signed-off-by: Abdifatah Suruur Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara [ sashal: replaced the unavailable smb_EIO2() call with -EIO ] Signed-off-by: Sasha Levin --- fs/cifs/smb2pdu.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index 2c7bcb768a64f..35e3be4933595 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -4236,6 +4236,7 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms, struct kvec iov[1]; struct kvec rsp_iov; unsigned int total_len; + u16 data_offset; int flags = CIFS_LOG_ERROR; struct cifs_ses *ses = io_parms->tcon->ses; @@ -4292,8 +4293,28 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms, *nbytes = 0; } + data_offset = rsp->DataOffset; + if (data_offset < io_parms->server->vals->read_rsp_size) { + /* + * win2k8 sometimes sends an offset of 0 when the read is beyond + * the EOF. Treat it as if the data starts just after the header, + * as handle_read_data() does. + */ + cifs_dbg(FYI, "data offset %u inside read response header\n", + data_offset); + data_offset = io_parms->server->vals->read_rsp_size; + } + + /* The data area must lie within the response actually received */ + if (*nbytes && (size_t)data_offset + *nbytes > rsp_iov.iov_len) { + cifs_dbg(FYI, "bad data offset %u length %u for response of %zu\n", + data_offset, *nbytes, rsp_iov.iov_len); + rc = -EIO; + *nbytes = 0; + } + if (*buf) { - memcpy(*buf, (char *)rsp + rsp->DataOffset, *nbytes); + memcpy(*buf, (char *)rsp + data_offset, *nbytes); free_rsp_buf(resp_buftype, rsp_iov.iov_base); } else if (resp_buftype != CIFS_NO_BUFFER) { *buf = rsp_iov.iov_base; -- 2.53.0