smb: client: fix potential NULL deref in parse_dfs_referrals()

If server returned no data for FSCTL_DFS_GET_REFERRALS, @dfs_rsp will
remain NULL and then parse_dfs_referrals() will dereference it.

Fix this by returning -EIO when no output data is returned.

Besides, we can't fix it in SMB2_ioctl() as some FSCTLs are allowed to
return no data as per MS-SMB2 2.2.32.

Fixes: 9d49640a21 ("CIFS: implement get_dfs_refer for SMB2+")
Cc: stable@vger.kernel.org
Reported-by: Robert Morris <rtm@csail.mit.edu>
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2023-12-05 21:49:29 -03:00 committed by Steve French
parent c54fc3a4f3
commit 92414333eb

View File

@ -2836,6 +2836,8 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses,
usleep_range(512, 2048);
} while (++retry_count < 5);
if (!rc && !dfs_rsp)
rc = -EIO;
if (rc) {
if (!is_retryable_error(rc) && rc != -ENOENT && rc != -EOPNOTSUPP)
cifs_tcon_dbg(VFS, "%s: ioctl error: rc=%d\n", __func__, rc);