4.9-stable review patch. If anyone has any objections, please let me know.
------------------
[ 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@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/cifs/cifsfs.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 87658f63b374..be84d49f2406 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -927,8 +927,8 @@ static int cifs_clone_file_range(struct file *src_file, loff_t off,
struct inode *src_inode = file_inode(src_file);
struct inode *target_inode = file_inode(dst_file);
struct cifsFileInfo *smb_file_src = src_file->private_data;
- struct cifsFileInfo *smb_file_target = dst_file->private_data;
- struct cifs_tcon *target_tcon = tlink_tcon(smb_file_target->tlink);
+ struct cifsFileInfo *smb_file_target;
+ struct cifs_tcon *target_tcon;
unsigned int xid;
int rc;
@@ -942,6 +942,9 @@ static int cifs_clone_file_range(struct file *src_file, loff_t off,
goto out;
}
+ smb_file_target = dst_file->private_data;
+ target_tcon = tlink_tcon(smb_file_target->tlink);
+
/*
* Note: cifs case is easier than btrfs since server responsible for
* checks for proper open modes and file type and if it wants
--
2.17.1
