3.16.74-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Christoph Probst <kernel@xxxxxxxxx>
commit 6a54b2e002c9d00b398d35724c79f9fe0d9b38fb upstream.
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@xxxxxxxxx>
Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
fs/cifs/smb2ops.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -1000,26 +1000,28 @@ smb21_set_oplock_level(struct cifsInodeI
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);
}
