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[mm,3/4] kasan: memset free track in qlink_free

Message ID d0943bd69fdfe27fbda20fde9b143e57c825546f.1702339432.git.andreyknvl@google.com (mailing list archive)
State New
Headers show
Series lib/stackdepot, kasan: fixes for stack eviction series | expand

Commit Message

andrey.konovalov@linux.dev Dec. 12, 2023, 12:14 a.m. UTC 
From: Andrey Konovalov <andreyknvl@google.com>

Instead of only zeroing out the stack depot handle when evicting the
free stack trace in qlink_free, zero out the whole track.

Do this just to produce a similar effect for alloc and free meta. The
other fields of the free track besides the stack trace handle are
considered invalid at this point anyway, so no harm in zeroing them out.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

---

This can be squashed into "kasan: use stack_depot_put for Generic mode"
or left standalone.
---
 mm/kasan/quarantine.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Marco Elver Dec. 12, 2023, 7:30 p.m. UTC | #1 
On Tue, 12 Dec 2023 at 01:14, <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@google.com>
>
> Instead of only zeroing out the stack depot handle when evicting the
> free stack trace in qlink_free, zero out the whole track.
>
> Do this just to produce a similar effect for alloc and free meta. The
> other fields of the free track besides the stack trace handle are
> considered invalid at this point anyway, so no harm in zeroing them out.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Marco Elver <elver@google.com>

> ---
>
> This can be squashed into "kasan: use stack_depot_put for Generic mode"
> or left standalone.
> ---
>  mm/kasan/quarantine.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
> index 265ca2bbe2dd..782e045da911 100644
> --- a/mm/kasan/quarantine.c
> +++ b/mm/kasan/quarantine.c
> @@ -157,7 +157,7 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
>         if (free_meta &&
>             *(u8 *)kasan_mem_to_shadow(object) == KASAN_SLAB_FREETRACK) {
>                 stack_depot_put(free_meta->free_track.stack);
> -               free_meta->free_track.stack = 0;
> +               __memset(&free_meta->free_track, 0, sizeof(free_meta->free_track));
>         }
>
>         /*
> --
> 2.25.1
>
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Patch

diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index 265ca2bbe2dd..782e045da911 100644
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -157,7 +157,7 @@  static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
 	if (free_meta &&
 	    *(u8 *)kasan_mem_to_shadow(object) == KASAN_SLAB_FREETRACK) {
 		stack_depot_put(free_meta->free_track.stack);
-		free_meta->free_track.stack = 0;
+		__memset(&free_meta->free_track, 0, sizeof(free_meta->free_track));
 	}
 
 	/*