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=1793910865; b=K7Eb4VIxuSgGV9rDi7gSP3ti6gLKTJH70cZNsivulsoi4vUM8wlvdvnlRVjuZY2Ovf/2 VJrd/3L22hkc4iHuStiGrreWvkGzZggBvp8zliK04JL+Cv/GVXwc9K5XRv88sBfOIYTzJ /Xb5siiynczH9riRMgGCgtVeeRIrLZznVV5c6f/GLKRvYHAIA85RiGVFEbbdX4alIak6G FVVO4D68qgRI6TbAbu5+Qccs2iB0loJFaTOc0Efvwv4v9AkgBYXBHk/FnFdCE16TZGYFr YZK2Nph+6ZxjfNLjB/PoFf/8bRC0t9scyANf0CeMlysHMAi+jrPU8+UE6+kVCS23+rg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793910865; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=5XEO4n/7XbbTsYODadw6MFY83CxH5HdToSc+DlpB1vA=; b=ARL9r4CdZRqu9L1+bFrgzBHcv7FhU6u7qt9lGfWRKWmTuKk5zZ+us9uGVvOSquiD5mN7 FIYjSt08kBw4Pmn5QY4adsCzhi/oeyQsOPvyPa+JKhaxaipNqtULXwxAvNtWC7FVcM0uf TaoawyV25NTZFk4LGJVGGAOGROe5yOF/IcXNmeHo86IT+69I1FgPM8xXyuGGw2mZaXy6L XkERNKJ7zvui7OcFhrcCRqFKtGIWjHt2aY1xkfGOkolLqfYwpjIpZKr7XVPGj/ITW+D6F JdWjbEpYtJompOZ1vpJFpfLBjORBXLbX5tNXe8GHXvW2OL2y/xpdW2oGGPJeE4MgeuQ== 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=e8F1yWmp; 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 96972606D802 for ; Thu, 5 Nov 2026 20:34:25 +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=e8F1yWmp Received: by smtp.kernel.org (Postfix) with ESMTPSA id 981101F0089F; Thu, 5 Nov 2026 20:34:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793910865; bh=5XEO4n/7XbbTsYODadw6MFY83CxH5HdToSc+DlpB1vA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=e8F1yWmpAY+zggpe63j9IK13Cqlu6VaHEZrcMuzwH2UsDaqNPmZEWBmbiXmHZTsUE RKhbenMFoD+NGkvURVS/L4LEIenujgc0tRK9nrQW1Xwk0pgAeubdvXBjwKS+6I2aBS K10QV5d2DRyt2QbsKxmIXqQMSVzaw/hWFI11TZSSo4aUfTzPpC8gbJi1sGaIoqHipa 3VfO+5PNqOhDVKwufI5gzviKgEyJdqCnBMAqTxZZ3Bjk1N8T1TjEIhpVidONC2Pa1n ZraMesyknQeAUZ/+gN86KJZX8SVhDrkMw16EPuMX7f0uSiEO+LtexZg/5m7EZc1pZk tMv43dOWMasjQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Abdifatah Suruur , Namjae Jeon , Paulo Alcantara , Sasha Levin Subject: [PATCH 6.6.y] smb: client: validate the data area in SMB2_read() Date: Thu, 5 Nov 2026 15:34:23 -0500 Message-ID: <20261105203345.2798304-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110452-postnasal-landlord-bb01@gregkh> References: <2026110452-postnasal-landlord-bb01@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() tracing helper call with rc = -EIO ] Signed-off-by: Sasha Levin --- fs/smb/client/smb2pdu.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index 1d8e491bb205c..dbc7e4936b4c0 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -4749,6 +4749,7 @@ 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; @@ -4806,8 +4807,28 @@ 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