* [PATCH v2] watchdog: avoid usage of iterator after loop
@ 2023-03-13 13:59 Jakob Koschel
2023-03-13 14:59 ` Guenter Roeck
0 siblings, 1 reply; 2+ messages in thread
From: Jakob Koschel @ 2023-03-13 13:59 UTC (permalink / raw)
To: Wim Van Sebroeck, Guenter Roeck
Cc: linux-watchdog, linux-kernel, Pietro Borrello,
Cristiano Giuffrida, Bos, H.J.,
Jakob Koschel
If potentially no valid element is found, 'p' would contain an invalid
pointer past the iterator loop. To ensure 'p' is valid under any
circumstances, the kfree() should be within the loop body.
Additionally, Linus proposed to avoid any use of the list iterator
variable after the loop, in the attempt to move the list iterator
variable declaration into the macro to avoid any potential misuse after
the loop [1].
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jkl820.git@gmail.com>
---
Changes in v2:
- avoid returning within the list iterator
- Link to v1: https://lore.kernel.org/r/20230301-watchdog-avoid-iter-after-loop-v1-1-851f583be9f7@gmail.com
---
drivers/watchdog/watchdog_pretimeout.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/watchdog/watchdog_pretimeout.c b/drivers/watchdog/watchdog_pretimeout.c
index 376a495ab80c..e5295c990fa1 100644
--- a/drivers/watchdog/watchdog_pretimeout.c
+++ b/drivers/watchdog/watchdog_pretimeout.c
@@ -207,10 +207,9 @@ void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
list_for_each_entry_safe(p, t, &pretimeout_list, entry) {
if (p->wdd == wdd) {
list_del(&p->entry);
+ kfree(p);
break;
}
}
spin_unlock_irq(&pretimeout_lock);
-
- kfree(p);
}
---
base-commit: c0927a7a5391f7d8e593e5e50ead7505a23cadf9
change-id: 20230301-watchdog-avoid-iter-after-loop-a197bf201435
Best regards,
--
Jakob Koschel <jkl820.git@gmail.com>
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] watchdog: avoid usage of iterator after loop
2023-03-13 13:59 [PATCH v2] watchdog: avoid usage of iterator after loop Jakob Koschel
@ 2023-03-13 14:59 ` Guenter Roeck
0 siblings, 0 replies; 2+ messages in thread
From: Guenter Roeck @ 2023-03-13 14:59 UTC (permalink / raw)
To: Jakob Koschel, Wim Van Sebroeck
Cc: linux-watchdog, linux-kernel, Pietro Borrello,
Cristiano Giuffrida, Bos, H.J.
On 3/13/23 06:59, Jakob Koschel wrote:
> If potentially no valid element is found, 'p' would contain an invalid
> pointer past the iterator loop. To ensure 'p' is valid under any
> circumstances, the kfree() should be within the loop body.
>
> Additionally, Linus proposed to avoid any use of the list iterator
> variable after the loop, in the attempt to move the list iterator
> variable declaration into the macro to avoid any potential misuse after
> the loop [1].
>
> Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
> Signed-off-by: Jakob Koschel <jkl820.git@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> ---
> Changes in v2:
> - avoid returning within the list iterator
> - Link to v1: https://lore.kernel.org/r/20230301-watchdog-avoid-iter-after-loop-v1-1-851f583be9f7@gmail.com
> ---
> drivers/watchdog/watchdog_pretimeout.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/watchdog_pretimeout.c b/drivers/watchdog/watchdog_pretimeout.c
> index 376a495ab80c..e5295c990fa1 100644
> --- a/drivers/watchdog/watchdog_pretimeout.c
> +++ b/drivers/watchdog/watchdog_pretimeout.c
> @@ -207,10 +207,9 @@ void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
> list_for_each_entry_safe(p, t, &pretimeout_list, entry) {
> if (p->wdd == wdd) {
> list_del(&p->entry);
> + kfree(p);
> break;
> }
> }
> spin_unlock_irq(&pretimeout_lock);
> -
> - kfree(p);
> }
>
> ---
> base-commit: c0927a7a5391f7d8e593e5e50ead7505a23cadf9
> change-id: 20230301-watchdog-avoid-iter-after-loop-a197bf201435
>
> Best regards,
^ permalink raw reply [flat|nested] 2+ messages in thread
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