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locks: use file_inode()

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(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: 4bacc9c923 ("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>
This commit is contained in:
Miklos Szeredi 2016-07-01 14:56:07 +02:00 committed by J. Bruce Fields
parent cb7d224f82
commit 6343a21208
1 changed files with 1 additions and 1 deletions
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2
fs/locks.c
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@ -1628,7 +1628,7 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
{
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;