tree 087190e997fe7854110c38056f172dbd0bfe05f6
parent e186413178a3d6a4d5c92ef5bced2e0b589a4649
author Colin Ian King <colin.king@canonical.com> 1541078070 +0000
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1543331377 +0100

cifs: don't dereference smb_file_target before null check

[ Upstream commit 8c6c9bed8773375b1d54ccca2911ec892c59db5d ]

There is a null check on dst_file->private data which suggests
it can be potentially null. However, before this check, pointer
smb_file_target is derived from dst_file->private and dereferenced
in the call to tlink_tcon, hence there is a potential null pointer
deference.

Fix this by assigning smb_file_target and target_tcon after the
null pointer sanity checks.

Detected by CoverityScan, CID#1475302 ("Dereference before null check")

Fixes: 04b38d601239 ("vfs: pull btrfs clone API to vfs layer")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>