This is a note to let you know that I've just added the patch titled
kernfs: fix potential NULL dereference in __kernfs_remove
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kernfs-fix-potential-null-dereference-in-__kernfs_re.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8dd6f07285f5df8a17ca5ee8b9072a3064b77f93
Author: Yushan Zhou <katrinzhou@xxxxxxxxxxx>
Date: Thu Jun 30 16:25:12 2022 +0800
kernfs: fix potential NULL dereference in __kernfs_remove
[ Upstream commit 72b5d5aef246a0387cefa23121dd90901c7a691a ]
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: 393c3714081a ("kernfs: switch global kernfs_rwsem lock to per-fs lock")
Signed-off-by: Yushan Zhou <katrinzhou@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220630082512.3482581-1-zys.zljxml@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 6eca72cfa1f2..1cc88ba6de90 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -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);
