On Sun, Apr 28, 2024 at 05:26:44PM +0300, Dan Carpenter wrote:
> Currently, if an automatically freed allocation is an error pointer that
> will lead to a crash. An example of this is in wm831x_gpio_dbg_show().
>
> 171 char *label __free(kfree) = gpiochip_dup_line_label(chip, i);
> 172 if (IS_ERR(label)) {
> 173 dev_err(wm831x->dev, "Failed to duplicate label\n");
> 174 continue;
> 175 }
>
> The auto clean up function should check for error pointers as well,
> otherwise we're going to keep hitting issues like this.
>
> Fixes: 54da6a092431 ("locking: Introduce __cleanup() based infrastructure")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> Obviously, the fixes tag isn't very fair but it will tell the -stable
> tools how far to backport this.
>
> include/linux/slab.h | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 4cc37ef22aae..5f5766219375 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -279,7 +279,7 @@ void kfree(const void *objp);
> void kfree_sensitive(const void *objp);
> size_t __ksize(const void *objp);
>
> -DEFINE_FREE(kfree, void *, if (_T) kfree(_T))
> +DEFINE_FREE(kfree, void *, if (!IS_ERR_OR_NULL(_T)) kfree(_T))
Wait, why do we check 'if (_T)' at all? kfree() already handles NULL
pointers just fine. I wouldn't be averse to making it handle error
pointers either.
> -DEFINE_FREE(kvfree, void *, if (_T) kvfree(_T))
> +DEFINE_FREE(kvfree, void *, if (!IS_ERR_OR_NULL(_T)) kvfree(_T))
Ditto kvfree(). Fixing kfree() would fix both of these.
