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cifs: Do not lookup hashed negative dentry in cifs_atomic_open

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We do not need to lookup a hashed negative directory since we have
already revalidated it before and have found it to be fine.

This also prevents a crash in cifs_lookup() when it attempts to rehash
the already hashed negative lookup dentry.

The patch has been tested using the reproducer at
https://bugzilla.redhat.com/show_bug.cgi?id=867344#c28

Cc: <stable@kernel.org> # 3.6.x
Reported-by: Vit Zahradka <vit.zahradka@tiscali.cz>
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
This commit is contained in:
Sachin Prabhu 2012-11-05 11:39:32 +00:00 committed by Jeff Layton
parent 36960e440c
commit 3798f47aa2
1 changed files with 10 additions and 1 deletions
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11
fs/cifs/dir.c
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@ -398,7 +398,16 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
* in network traffic in the other paths.
*/
if (!(oflags & O_CREAT)) {
struct dentry *res = cifs_lookup(inode, direntry, 0);
struct dentry *res;
/*
* Check for hashed negative dentry. We have already revalidated
* the dentry and it is fine. No need to perform another lookup.
*/
if (!d_unhashed(direntry))
return -ENOENT;
res = cifs_lookup(inode, direntry, 0);
if (IS_ERR(res))
return PTR_ERR(res);