On Tue 06-06-23 11:32:53, Dan Carpenter wrote:
> Hello Jan Kara,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch afb4adc7c3ef: "fs: Restrict lock_two_nondirectories() to
> non-directory inodes" from Jun 1, 2023, leads to the following Smatch
> complaint:
>
> fs/inode.c:1174 unlock_two_nondirectories()
> warn: variable dereferenced before check 'inode1' (see line 1172)
>
> fs/inode.c:1176 unlock_two_nondirectories()
> warn: variable dereferenced before check 'inode2' (see line 1173)
Indeed, thanks for spotting this! Luckily there are currently no in-tree
users passing NULL. Attached patch fixes this. Christian, can you please
add this to your branch or squash it into the fixed commit? Thanks!
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
>From 4afde047fb4408553b9d2c548ebe355db7c95f0f Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@xxxxxxx>
Date: Tue, 6 Jun 2023 11:52:33 +0200
Subject: [PATCH] fs: Fixup unlock_two_nondirectories() for NULL inodes
When inode is NULL, we cannot WARN on S_ISDIR(inode->i_mode) as that
would be a NULL ptr dereference. Move the warnings below the NULL
checks.
Fixes: afb4adc7c3ef ("fs: Restrict lock_two_nondirectories() to non-directory inodes")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/inode.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c
index e2707ee88459..53ae3b76d232 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1169,12 +1169,14 @@ EXPORT_SYMBOL(lock_two_nondirectories);
*/
void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
{
- WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
- WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
- if (inode1)
+ if (inode1) {
+ WARN_ON_ONCE(S_ISDIR(inode1->i_mode));
inode_unlock(inode1);
- if (inode2 && inode2 != inode1)
+ }
+ if (inode2 && inode2 != inode1) {
+ WARN_ON_ONCE(S_ISDIR(inode2->i_mode));
inode_unlock(inode2);
+ }
}
EXPORT_SYMBOL(unlock_two_nondirectories);
--
2.35.3
