[PATCH 19/20] orangefs_d_revalidate(): use stable parent inode and name passed by caller

[Al Viro <viro@zeniv.linux.org.uk>]

->d_name use is a UAF.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/orangefs/dcache.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/fs/orangefs/dcache.c b/fs/orangefs/dcache.c
index c32c9a86e8d0..060c94e9759b 100644
--- a/fs/orangefs/dcache.c
+++ b/fs/orangefs/dcache.c
@@ -13,10 +13,9 @@
 #include "orangefs-kernel.h"
 
 /* Returns 1 if dentry can still be trusted, else 0. */
-static int orangefs_revalidate_lookup(struct dentry *dentry)
+static int orangefs_revalidate_lookup(struct inode *parent_inode, const struct qstr *name,
+				      struct dentry *dentry)
 {
-	struct dentry *parent_dentry = dget_parent(dentry);
-	struct inode *parent_inode = parent_dentry->d_inode;
 	struct orangefs_inode_s *parent = ORANGEFS_I(parent_inode);
 	struct inode *inode = dentry->d_inode;
 	struct orangefs_kernel_op_s *new_op;
@@ -26,14 +25,12 @@ static int orangefs_revalidate_lookup(struct dentry *dentry)
 	gossip_debug(GOSSIP_DCACHE_DEBUG, "%s: attempting lookup.\n", __func__);
 
 	new_op = op_alloc(ORANGEFS_VFS_OP_LOOKUP);
-	if (!new_op) {
-		ret = -ENOMEM;
-		goto out_put_parent;
-	}
+	if (!new_op)
+		return -ENOMEM;
 
 	new_op->upcall.req.lookup.sym_follow = ORANGEFS_LOOKUP_LINK_NO_FOLLOW;
 	new_op->upcall.req.lookup.parent_refn = parent->refn;
-	strscpy(new_op->upcall.req.lookup.d_name, dentry->d_name.name);
+	strscpy(new_op->upcall.req.lookup.d_name, name->name);
 
 	gossip_debug(GOSSIP_DCACHE_DEBUG,
 		     "%s:%s:%d interrupt flag [%d]\n",
@@ -78,8 +75,6 @@ static int orangefs_revalidate_lookup(struct dentry *dentry)
 	ret = 1;
 out_release_op:
 	op_release(new_op);
-out_put_parent:
-	dput(parent_dentry);
 	return ret;
 out_drop:
 	gossip_debug(GOSSIP_DCACHE_DEBUG, "%s:%s:%d revalidate failed\n",
@@ -115,7 +110,7 @@ static int orangefs_d_revalidate(struct inode *dir, const struct qstr *name,
 	 * If this passes, the positive dentry still exists or the negative
 	 * dentry still does not exist.
 	 */
-	if (!orangefs_revalidate_lookup(dentry))
+	if (!orangefs_revalidate_lookup(dir, name, dentry))
 		return 0;
 
 	/* We do not need to continue with negative dentries. */
-- 
2.39.5