diff options
| author | Christoph Probst <kernel@probst.it> | 2019-05-07 17:16:40 +0200 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2019-05-07 23:24:55 -0500 |
| commit | 6a54b2e002c9d00b398d35724c79f9fe0d9b38fb (patch) | |
| tree | 15337da48020ddeb9265edcad0abf0255895d881 | |
| parent | 26ea888f6282b0f5c1977d8ddb2fff1ea0238bd7 (diff) | |
| download | linux-6a54b2e002c9d00b398d35724c79f9fe0d9b38fb.tar.bz2 | |
cifs: fix strcat buffer overflow and reduce raciness in smb21_set_oplock_level()
Change strcat to strncpy in the "None" case to fix a buffer overflow
when cinode->oplock is reset to 0 by another thread accessing the same
cinode. It is never valid to append "None" to any other message.
Consolidate multiple writes to cinode->oplock to reduce raciness.
Signed-off-by: Christoph Probst <kernel@probst.it>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
| -rw-r--r-- | fs/cifs/smb2ops.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 860dd1696830..4313cb04549e 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -2974,26 +2974,28 @@ smb21_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock, unsigned int epoch, bool *purge_cache) { char message[5] = {0}; + unsigned int new_oplock = 0; oplock &= 0xFF; if (oplock == SMB2_OPLOCK_LEVEL_NOCHANGE) return; - cinode->oplock = 0; if (oplock & SMB2_LEASE_READ_CACHING_HE) { - cinode->oplock |= CIFS_CACHE_READ_FLG; + new_oplock |= CIFS_CACHE_READ_FLG; strcat(message, "R"); } if (oplock & SMB2_LEASE_HANDLE_CACHING_HE) { - cinode->oplock |= CIFS_CACHE_HANDLE_FLG; + new_oplock |= CIFS_CACHE_HANDLE_FLG; strcat(message, "H"); } if (oplock & SMB2_LEASE_WRITE_CACHING_HE) { - cinode->oplock |= CIFS_CACHE_WRITE_FLG; + new_oplock |= CIFS_CACHE_WRITE_FLG; strcat(message, "W"); } - if (!cinode->oplock) - strcat(message, "None"); + if (!new_oplock) + strncpy(message, "None", sizeof(message)); + + cinode->oplock = new_oplock; cifs_dbg(FYI, "%s Lease granted on inode %p\n", message, &cinode->vfs_inode); } |