Thread (71 messages) 71 messages, 6 authors, 2020-11-16

Re: [PATCH RFC v2 20/21] kasan: simplify assign_tag and set_tag calls

From: Dmitry Vyukov <dvyukov@google.com>
Date: 2020-10-28 22:19:11
Also in: linux-mm, lkml

On Thu, Oct 22, 2020 at 3:20 PM Andrey Konovalov [off-list ref] wrote:
set_tag() already ignores the tag for the generic mode, so just call it
as is. Add a check for the generic mode to assign_tag(), and simplify its
call in ____kasan_kmalloc().

Signed-off-by: Andrey Konovalov <redacted>
Link: https://linux-review.googlesource.com/id/I18905ca78fb4a3d60e1a34a4ca00247272480438
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
quoted hunk ↗ jump to hunk
---
 mm/kasan/common.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 983383ebe32a..3cd56861eb11 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -235,6 +235,9 @@ void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
 static u8 assign_tag(struct kmem_cache *cache, const void *object,
                        bool init, bool keep_tag)
 {
+       if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+               return 0xff;
+
        /*
         * 1. When an object is kmalloc()'ed, two hooks are called:
         *    kasan_slab_alloc() and kasan_kmalloc(). We assign the
@@ -277,8 +280,8 @@ void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
                __memset(alloc_meta, 0, sizeof(*alloc_meta));
        }

-       if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS))
-               object = set_tag(object, assign_tag(cache, object, true, false));
+       /* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
+       object = set_tag(object, assign_tag(cache, object, true, false));

        return (void *)object;
 }
@@ -360,9 +363,7 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
                                KASAN_GRANULE_SIZE);
        redzone_end = round_up((unsigned long)object + cache->object_size,
                                KASAN_GRANULE_SIZE);
-
-       if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS))
-               tag = assign_tag(cache, object, false, keep_tag);
+       tag = assign_tag(cache, object, false, keep_tag);

        /*
         * Don't unpoison the object when keeping the tag. Tag is kept for:
--
2.29.0.rc1.297.gfa9743e501-goog
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help