cifs: Do not lookup hashed negative dentry in cifs_atomic_open (3798f47a) · Commits · e / devices / android_kernel_teracube_emerald

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>

fs/cifs/dir.c

+10 −1

Original line number	Original line	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.		* in network traffic in the other paths.
	*/		*/
	if (!(oflags & O_CREAT)) {		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))		if (IS_ERR(res))
	return PTR_ERR(res);		return PTR_ERR(res);