4.18-stable review patch. If anyone has any objections, please let me know.
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From: Dan Carpenter dan.carpenter@oracle.com
commit 56446f218af1133c802dad8e9e116f07f381846c upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/cifs/smb2pdu.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-)
--- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -3492,33 +3492,38 @@ num_entries(char *bufstart, char *end_of 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; }