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configfs: Fix potential NULL d_inode dereference

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Code that does this:

		if (!(d_unhashed(dentry) && dentry->d_inode)) {
			...
			simple_unlink(parent->d_inode, dentry);
		}

is broken because:

    !(d_unhashed(dentry) && dentry->d_inode)

is equivalent to:

    !d_unhashed(dentry) || !dentry->d_inode

so it is possible to get into simple_unlink() with dentry->d_inode == NULL.

simple_unlink(), however, assumes dentry->d_inode cannot be NULL.

I think that what was meant is this:

    !d_unhashed(dentry) && dentry->d_inode

and that the logical-not operator or the final close-bracket was misplaced.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells 2015-01-27 15:18:39 +00:00 committed by Al Viro
parent a457ac2854
commit 112fc894a7
1 changed files with 1 additions and 1 deletions
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2
fs/configfs/inode.c
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@ -236,7 +236,7 @@ void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
if (dentry) {
spin_lock(&dentry->d_lock);
if (!(d_unhashed(dentry) && dentry->d_inode)) {
if (!d_unhashed(dentry) && dentry->d_inode) {
dget_dlock(dentry);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);