Commit 72b5d5ae authored by Yushan Zhou's avatar Yushan Zhou Committed by Greg Kroah-Hartman
Browse files

kernfs: fix potential NULL dereference in __kernfs_remove 



When lockdep is enabled, lockdep_assert_held_write would
cause potential NULL pointer dereference.

Fix the following smatch warnings:

fs/kernfs/dir.c:1353 __kernfs_remove() warn: variable dereferenced before check 'kn' (see line 1346)

Fixes: 393c3714 ("kernfs: switch global kernfs_rwsem lock to per-fs lock")
Signed-off-by: default avatarYushan Zhou <katrinzhou@tencent.com>
Link: https://lore.kernel.org/r/20220630082512.3482581-1-zys.zljxml@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c882716b

fs/kernfs/dir.c

+5 −2
Original line number Diff line number Diff line
@@ -1343,14 +1343,17 @@ static void __kernfs_remove(struct kernfs_node *kn) 
{

	struct kernfs_node *pos;



	/* Short-circuit if non-root @kn has already finished removal. */

	if (!kn)

		return;



	lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem);



	/*

	 * Short-circuit if non-root @kn has already finished removal.

	 * This is for kernfs_remove_self() which plays with active ref

	 * after removal.

	 */

	if (!kn || (kn->parent && RB_EMPTY_NODE(&kn->rb)))

	if (kn->parent && RB_EMPTY_NODE(&kn->rb))

		return;



	pr_debug("kernfs %s: removing\n", kn->name);