Messages in this thread Patch in this message | | | From | zys.zljxml@gmail ... | Subject | [PATCH] kernfs: fix potential NULL dereference in __kernfs_remove | Date | Thu, 30 Jun 2022 12:00:47 +0800 |
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From: katrinzhou <katrinzhou@tencent.com>
When lockdep is enabled, lockdep_assert_held_write would cause potential NULL pointer dereference.
Fix the folloeing smatch warnings:
fs/kernfs/dir.c:1353 __kernfs_remove() warn: variable dereferenced before check 'kn' (see line 1346)
Signed-off-by: katrinzhou <katrinzhou@tencent.com> --- fs/kernfs/dir.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
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); -- 2.27.0
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