github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-10-08 03:26:02 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()

Browse Source 
coalesce_t2() computes data pointers directly from server-supplied
DataOffset fields with no validation against buffer bounds:

  data_area_of_tgt = (char *)&pSMBt->hdr.Protocol +
                     get_unaligned_le16(&pSMBt->t2_rsp.DataOffset);
  data_area_of_src = (char *)&pSMBs->hdr.Protocol +
                     get_unaligned_le16(&pSMBs->t2_rsp.DataOffset);
  data_area_of_tgt += total_in_tgt;
  ...
  memcpy(data_area_of_tgt, data_area_of_src, total_in_src);

A small DataOffset can push a pointer below the actual byte area,
overwriting header fields; a large one can push it past the buffer
end, causing out-of-bounds heap reads (source) or writes (target).
The BCC overflow guard does not prevent this: BCC reflects how much
data is present, while DataOffset controls where in the buffer it
starts.

The "validate target area" comment present since the function was
first written in 2005 was a placeholder that was never implemented.

Add lower- and upper-bound checks for both data pointers before the
memcpy, and before any target header fields are modified.

Fixes: e4eb295d38 ("[PATCH] cifs: Handle multiple response transact2 part 1 of 2")
Cc: stable@vger.kernel.org
Reported-by: Shen Yongchao <grayhat@foxmail.com>
Signed-off-by: Frank Sorenson <sorenson@redhat.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
This commit is contained in:
Frank Sorenson 2026-08-11 21:41:26 -05:00 committed by Paulo Alcantara
parent 43549eb842
commit 6343c1da56
1 changed files with 20 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
fs/smb/client/smb1transport.c
View File

@ -375,12 +375,31 @@ coalesce_t2(char *second_buf, struct smb_hdr *target_hdr, unsigned int *pdu_len)
data_area_of_tgt = (char *)&pSMBt->hdr.Protocol +
get_unaligned_le16(&pSMBt->t2_rsp.DataOffset);
/* validate target area */
data_area_of_src = (char *)&pSMBs->hdr.Protocol +
get_unaligned_le16(&pSMBs->t2_rsp.DataOffset);
data_area_of_tgt += total_in_tgt;
/*
* DataOffset fields are server-supplied and not validated against
* buffer bounds; check both data pointers before mutating the
* target header.
*/
if (data_area_of_tgt < (char *)target_hdr +
sizeof(struct smb_t2_rsp) + sizeof(__le16) ||
data_area_of_tgt + total_in_src >
(char *)target_hdr + CIFSMaxBufSize + MAX_CIFS_HDR_SIZE) {
cifs_dbg(VFS, "%s: target data area out of bounds\n", __func__);
return -EPROTO;
}
if (data_area_of_src < second_buf +
sizeof(struct smb_t2_rsp) + sizeof(__le16) ||
data_area_of_src + total_in_src >
second_buf + smbCalcSize((struct smb_hdr *)second_buf)) {
cifs_dbg(VFS, "%s: secondary data area out of bounds\n", __func__);
return -EPROTO;
}
total_in_tgt += total_in_src;
/* is the result too big for the field? */
if (total_in_tgt > USHRT_MAX) {