diff options
| author |   Dan Carpenter <dan.carpenter@oracle.com> | 2018-09-06 12:48:22 +0300 |
|---|---|---|
| committer |   Steve French <stfrench@microsoft.com> | 2018-09-12 09:32:07 -0500 |
| commit | 56446f218af1133c802dad8e9e116f07f381846c (patch) | |
| tree | 1f35fa87689fcfdb7eead9d9e0b12164ce384e33 /fs | |
| parent | cifs: prevent integer overflow in nxt_dir_entry() (diff) | |
| download | linux-dev-56446f218af1133c802dad8e9e116f07f381846c.tar.xz linux-dev-56446f218af1133c802dad8e9e116f07f381846c.zip | |
CIFS: fix wrapping bugs in num_entries()
The problem is that "entryptr + next_offset" and "entryptr + len + size"
can wrap. I ended up changing the type of "entryptr" because it makes
the math easier when we don't have to do so much casting.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/cifs/smb2pdu.c | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index c08acfc77abc..6f0e6b42599c 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -3577,33 +3577,38 @@ num_entries(char *bufstart, char *end_of_buf, char **lastentry, size_t size) int len; unsigned int entrycount = 0; unsigned int next_offset = 0; - FILE_DIRECTORY_INFO *entryptr; + char *entryptr; + FILE_DIRECTORY_INFO *dir_info; if (bufstart == NULL) return 0; - entryptr = (FILE_DIRECTORY_INFO *)bufstart; + entryptr = bufstart; while (1) { - entryptr = (FILE_DIRECTORY_INFO *) - ((char *)entryptr + next_offset); - - if ((char *)entryptr + size > end_of_buf) { + if (entryptr + next_offset < entryptr || + entryptr + next_offset > end_of_buf || + entryptr + next_offset + size > end_of_buf) { cifs_dbg(VFS, "malformed search entry would overflow\n"); break; } - len = le32_to_cpu(entryptr->FileNameLength); - if ((char *)entryptr + len + size > end_of_buf) { + entryptr = entryptr + next_offset; + dir_info = (FILE_DIRECTORY_INFO *)entryptr; + + len = le32_to_cpu(dir_info->FileNameLength); + if (entryptr + len < entryptr || + entryptr + len > end_of_buf || + entryptr + len + size > end_of_buf) { cifs_dbg(VFS, "directory entry name would overflow frame end of buf %p\n", end_of_buf); break; } - *lastentry = (char *)entryptr; + *lastentry = entryptr; entrycount++; - next_offset = le32_to_cpu(entryptr->NextEntryOffset); + next_offset = le32_to_cpu(dir_info->NextEntryOffset); if (!next_offset) break; } |