2024-03-14 13:47:33

by Nikita Kiryushin

Subject: [PATCH] fanotify: remove unneeded sub-zero check for unsigned value

Unsigned size_t len in copy_fid_info_to_user is checked
for negative value. This check is redundant as it is
always false.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 5e469c830fdb ("fanotify: copy event fid info to user")
Signed-off-by: Nikita Kiryushin <[email protected]>
---
fs/notify/fanotify/fanotify_user.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index fbdc63cc10d9..4201723357cf 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -502,7 +502,7 @@ static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
}

/* Pad with 0's */
- WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN);
+ WARN_ON_ONCE(len >= FANOTIFY_EVENT_ALIGN);
if (len > 0 && clear_user(buf, len))
return -EFAULT;

--
2.34.1

2024-03-25 19:17:21

by Jan Kara

Subject: Re: [PATCH] fanotify: remove unneeded sub-zero check for unsigned value

On Thu 14-03-24 16:36:56, Nikita Kiryushin wrote:
>
> Unsigned size_t len in copy_fid_info_to_user is checked
> for negative value. This check is redundant as it is
> always false.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 5e469c830fdb ("fanotify: copy event fid info to user")
> Signed-off-by: Nikita Kiryushin <[email protected]>

Looks good. Added to my tree. Thanks!

Honza

> ---
> fs/notify/fanotify/fanotify_user.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index fbdc63cc10d9..4201723357cf 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -502,7 +502,7 @@ static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
> }
> /* Pad with 0's */
> - WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN);
> + WARN_ON_ONCE(len >= FANOTIFY_EVENT_ALIGN);
> if (len > 0 && clear_user(buf, len))
> return -EFAULT;
> --
> 2.34.1
>
--
Jan Kara <[email protected]>
SUSE Labs, CR