Commit c3724b12 authored Apr 11, 2007 by Jeff Mahoney Committed by Linus Torvalds Apr 12, 2007

[PATCH] autofs4: fix race in unhashed dentry code



Commit f50b6f86 introduced a race in
autofs4 between autofs_lookup_unhashed() and autofs_dentry_release().

autofs_dentry_release() ends up clearing the ->dentry and ->inode members
of autofs_info before removing it from the rehash list.  The list is
protected by the rehash lock in both functions, but since
autofs_dentry_release() starts tearing the autofs_info struct down before
removing it from the list, autofs_lookup_unhashed() can get a autofs_info
with a NULL dentry.

This patch moves the clearing of ->dentry and ->inode after the removal
from the rehash list.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 6d205f12

fs/autofs4/root.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -470,9 +470,6 @@ void autofs4_dentry_release(struct dentry *de)
		if (inf) {
		struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);

		inf->dentry = NULL;
		inf->inode = NULL;

		if (sbi) {
		spin_lock(&sbi->rehash_lock);
		if (!list_empty(&inf->rehash))
		@@ -480,6 +477,9 @@ void autofs4_dentry_release(struct dentry *de)
		spin_unlock(&sbi->rehash_lock);
		}

		inf->dentry = NULL;
		inf->inode = NULL;

		autofs4_free_ino(inf);
		}
		}