Commit c1892c37 authored Aug 03, 2016 by Miklos Szeredi

vfs: fix deadlock in file_remove_privs() on overlayfs



file_remove_privs() is called with inode lock on file_inode(), which
proceeds to calling notify_change() on file->f_path.dentry.  Which triggers
the WARN_ON_ONCE(!inode_is_locked(inode)) in addition to deadlocking later
when ovl_setattr tries to lock the underlying inode again.

Fix this mess by not mixing the layers, but doing everything on underlying
dentry/inode.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 07a2daab ("ovl: Copy up underlying inode's ->i_mode to overlay inode")
Cc: <stable@vger.kernel.org>

parent 523d939e

fs/inode.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -1740,8 +1740,8 @@ static int __remove_privs(struct dentry *dentry, int kill)
		*/
		int file_remove_privs(struct file *file)
		{
		struct dentry *dentry = file->f_path.dentry;
		struct inode *inode = d_inode(dentry);
		struct dentry *dentry = file_dentry(file);
		struct inode *inode = file_inode(file);
		int kill;
		int error = 0;

		@@ -1749,7 +1749,7 @@ int file_remove_privs(struct file *file)
		if (IS_NOSEC(inode))
		return 0;

		kill = file_needs_remove_privs(file);
		kill = dentry_needs_remove_privs(dentry);
		if (kill < 0)
		return kill;
		if (kill)