locks: use file_inode()
(Another one for the f_path debacle.)
ltp fcntl33 testcase caused an Oops in selinux_file_send_sigiotask.
The reason is that generic_add_lease() used filp->f_path.dentry->inode
while all the others use file_inode(). This makes a difference for files
opened on overlayfs since the former will point to the overlay inode the
latter to the underlying inode.
So generic_add_lease() added the lease to the overlay inode and
generic_delete_lease() removed it from the underlying inode. When the file
was released the lease remained on the overlay inode's lock list, resulting
in use after free.
Reported-by: Eryu Guan <eguan@redhat.com>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Cc: <stable@vger.kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/locks.c b/fs/locks.c
index 7c5f91b..ee1b15f 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1628,7 +1628,7 @@
{
struct file_lock *fl, *my_fl = NULL, *lease;
struct dentry *dentry = filp->f_path.dentry;
- struct inode *inode = dentry->d_inode;
+ struct inode *inode = file_inode(filp);
struct file_lock_context *ctx;
bool is_deleg = (*flp)->fl_flags & FL_DELEG;
int error;