| Message ID | 20230301-watchdog-avoid-iter-after-loop-v2-1-8411e3bbe0de@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] watchdog: avoid usage of iterator after loop | expand |
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,
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); }
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(-) --- base-commit: c0927a7a5391f7d8e593e5e50ead7505a23cadf9 change-id: 20230301-watchdog-avoid-iter-after-loop-a197bf201435 Best regards,