[CIFS] Check that last search entry resume key is valid
Jeff's recent patch to add a last_entry field in the search structure
to better construct resume keys did not validate that the server
sent us a plausible pointer to the last entry. This adds that.
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 7b00a16..6f4ffe1 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -3614,6 +3614,8 @@
/* BB remember to free buffer if error BB */
rc = validate_t2((struct smb_t2_rsp *)pSMBr);
if (rc == 0) {
+ unsigned int lnoff;
+
if (pSMBr->hdr.Flags2 & SMBFLG2_UNICODE)
psrch_inf->unicode = true;
else
@@ -3636,8 +3638,17 @@
le16_to_cpu(parms->SearchCount);
psrch_inf->index_of_last_entry = 2 /* skip . and .. */ +
psrch_inf->entries_in_buffer;
+ lnoff = le16_to_cpu(parms->LastNameOffset);
+ if (tcon->ses->server->maxBuf - MAX_CIFS_HDR_SIZE <
+ lnoff) {
+ cERROR(1, ("ignoring corrupt resume name"));
+ psrch_inf->last_entry = NULL;
+ return rc;
+ }
+
psrch_inf->last_entry = psrch_inf->srch_entries_start +
- le16_to_cpu(parms->LastNameOffset);
+ lnoff;
+
*pnetfid = parms->SearchHandle;
} else {
cifs_buf_release(pSMB);
@@ -3727,6 +3738,8 @@
rc = validate_t2((struct smb_t2_rsp *)pSMBr);
if (rc == 0) {
+ unsigned int lnoff;
+
/* BB fixme add lock for file (srch_info) struct here */
if (pSMBr->hdr.Flags2 & SMBFLG2_UNICODE)
psrch_inf->unicode = true;
@@ -3753,8 +3766,16 @@
le16_to_cpu(parms->SearchCount);
psrch_inf->index_of_last_entry +=
psrch_inf->entries_in_buffer;
- psrch_inf->last_entry = psrch_inf->srch_entries_start +
- le16_to_cpu(parms->LastNameOffset);
+ lnoff = le16_to_cpu(parms->LastNameOffset);
+ if (tcon->ses->server->maxBuf - MAX_CIFS_HDR_SIZE <
+ lnoff) {
+ cERROR(1, ("ignoring corrupt resume name"));
+ psrch_inf->last_entry = NULL;
+ return rc;
+ } else
+ psrch_inf->last_entry =
+ psrch_inf->srch_entries_start + lnoff;
+
/* cFYI(1,("fnxt2 entries in buf %d index_of_last %d",
psrch_inf->entries_in_buffer, psrch_inf->index_of_last_entry)); */