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[PATCH] autofs4: fix race in unhashed dentry code

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Commit f50b6f8691 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>
This commit is contained in:
Jeff Mahoney 2007-04-11 23:28:46 -07:00 committed by Linus Torvalds
parent 6d205f1205
commit c3724b129b
1 changed files with 3 additions and 3 deletions
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6
fs/autofs4/root.c
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@ -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);
}
}