Re: [PATCH] perf trace: Fix IS_ERR() vs NULL check bug

[Howard Chu]

Hi wangguangju,

On Thu, Feb 26, 2026 at 4:23 AM <wangguangju@xxxxxxxx> wrote:
>
> From: wangguangju <wangguangju@xxxxxxxx>
>
> The alloc_syscall_stats() function always returns an error pointer
> (ERR_PTR) on failure.
>
> So replace NULL check with IS_ERR() check after calling
> delete_syscall_stats() function.

Thanks, syscall_stats is never NULL after alloc_syscall_stats(), and
it seems like perf now frees the hashmap using the error pointer,
pretty dangerous.

>
> Signed-off-by: wangguangju <wangguangju@xxxxxxxx>

Reviewed-by: Howard Chu <howardchu95@xxxxxxxxx>

Thanks,
Howard

> ---
>  tools/perf/builtin-trace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index 311d9da9896a..295b272c6c29 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -1573,7 +1573,7 @@ static void delete_syscall_stats(struct hashmap *syscall_stats)
>         struct hashmap_entry *pos;
>         size_t bkt;
>
> -       if (syscall_stats == NULL)
> +       if (IS_ERR(syscall_stats))
>                 return;
>
>         hashmap__for_each_entry(syscall_stats, pos, bkt)
> --
> 2.43.0
>
>
>