Commit 3798f47a authored Nov 05, 2012 by Sachin Prabhu Committed by Jeff Layton Nov 05, 2012

cifs: Do not lookup hashed negative dentry in cifs_atomic_open

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>

parent 36960e44

fs/cifs/dir.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -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);

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