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cifs: prevent integer overflow in nxt_dir_entry()

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The "old_entry + le32_to_cpu(pDirInfo->NextEntryOffset)" can wrap
around so I have added a check for integer overflow.

Reported-by: Dr Silvio Cesare of InfoSect <silvio.cesare@gmail.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
This commit is contained in:
Dan Carpenter 2018-09-06 12:47:51 +03:00 committed by Steve French
parent 5890184d2b
commit 8ad8aa3535
1 changed files with 9 additions and 2 deletions
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11
fs/cifs/readdir.c
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@ -376,8 +376,15 @@ static char *nxt_dir_entry(char *old_entry, char *end_of_smb, int level)
new_entry = old_entry + sizeof(FIND_FILE_STANDARD_INFO) +
pfData->FileNameLength;
} else
new_entry = old_entry + le32_to_cpu(pDirInfo->NextEntryOffset);
} else {
u32 next_offset = le32_to_cpu(pDirInfo->NextEntryOffset);
if (old_entry + next_offset < old_entry) {
cifs_dbg(VFS, "invalid offset %u\n", next_offset);
return NULL;
}
new_entry = old_entry + next_offset;
}
cifs_dbg(FYI, "new entry %p old entry %p\n", new_entry, old_entry);
/* validate that new_entry is not past end of SMB */
if (new_entry >= end_of_smb) {