kasan: drop CONFIG_KASAN_TAGS_IDENTIFY

Drop CONFIG_KASAN_TAGS_IDENTIFY and related code to simplify making
changes to the reporting code.

The dropped functionality will be restored in the following patches in
this series.

Link: https://lkml.kernel.org/r/4c66ba98eb237e9ed9312c19d423bbcf4ecf88f8.1662411799.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index f0973da..ca09b1c 100644 (file)
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -167,14 +167,6 @@ config KASAN_STACK
          as well, as it adds inline-style instrumentation that is run
          unconditionally.
 
-config KASAN_TAGS_IDENTIFY
-       bool "Memory corruption type identification"
-       depends on KASAN_SW_TAGS || KASAN_HW_TAGS
-       help
-         Enables best-effort identification of the bug types (use-after-free
-         or out-of-bounds) at the cost of increased memory consumption.
-         Only applicable for the tag-based KASAN modes.
-
 config KASAN_VMALLOC
        bool "Check accesses to vmalloc allocations"
        depends on HAVE_ARCH_KASAN_VMALLOC

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index d401fb7..15c7187 100644 (file)
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -169,23 +169,13 @@ struct kasan_track {
        depot_stack_handle_t stack;
 };
 
-#if defined(CONFIG_KASAN_TAGS_IDENTIFY) && defined(CONFIG_KASAN_SW_TAGS)
-#define KASAN_NR_FREE_STACKS 5
-#else
-#define KASAN_NR_FREE_STACKS 1
-#endif
-
 struct kasan_alloc_meta {
        struct kasan_track alloc_track;
        /* Generic mode stores free track in kasan_free_meta. */
 #ifdef CONFIG_KASAN_GENERIC
        depot_stack_handle_t aux_stack[2];
 #else
-       struct kasan_track free_track[KASAN_NR_FREE_STACKS];
-#endif
-#ifdef CONFIG_KASAN_TAGS_IDENTIFY
-       u8 free_pointer_tag[KASAN_NR_FREE_STACKS];
-       u8 free_track_idx;
+       struct kasan_track free_track;
 #endif
 };
 

diff --git a/mm/kasan/report_tags.c b/mm/kasan/report_tags.c
index e25d216..35cf3ca 100644 (file)
--- a/mm/kasan/report_tags.c
+++ b/mm/kasan/report_tags.c
@@ -5,37 +5,9 @@
  */
 
 #include "kasan.h"
-#include "../slab.h"
 
 const char *kasan_get_bug_type(struct kasan_report_info *info)
 {
-#ifdef CONFIG_KASAN_TAGS_IDENTIFY
-       struct kasan_alloc_meta *alloc_meta;
-       struct kmem_cache *cache;
-       struct slab *slab;
-       const void *addr;
-       void *object;
-       u8 tag;
-       int i;
-
-       tag = get_tag(info->access_addr);
-       addr = kasan_reset_tag(info->access_addr);
-       slab = kasan_addr_to_slab(addr);
-       if (slab) {
-               cache = slab->slab_cache;
-               object = nearest_obj(cache, slab, (void *)addr);
-               alloc_meta = kasan_get_alloc_meta(cache, object);
-
-               if (alloc_meta) {
-                       for (i = 0; i < KASAN_NR_FREE_STACKS; i++) {
-                               if (alloc_meta->free_pointer_tag[i] == tag)
-                                       return "use-after-free";
-                       }
-               }
-               return "out-of-bounds";
-       }
-#endif
-
        /*
         * If access_size is a negative number, then it has reason to be
         * defined as out-of-bounds bug type.

diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
index 1ba3c83..e0e5de8 100644 (file)
--- a/mm/kasan/tags.c
+++ b/mm/kasan/tags.c
@@ -30,39 +30,22 @@ void kasan_save_free_info(struct kmem_cache *cache,
                                void *object, u8 tag)
 {
        struct kasan_alloc_meta *alloc_meta;
-       u8 idx = 0;
 
        alloc_meta = kasan_get_alloc_meta(cache, object);
        if (!alloc_meta)
                return;
 
-#ifdef CONFIG_KASAN_TAGS_IDENTIFY
-       idx = alloc_meta->free_track_idx;
-       alloc_meta->free_pointer_tag[idx] = tag;
-       alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS;
-#endif
-
-       kasan_set_track(&alloc_meta->free_track[idx], GFP_NOWAIT);
+       kasan_set_track(&alloc_meta->free_track, GFP_NOWAIT);
 }
 
 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
                                void *object, u8 tag)
 {
        struct kasan_alloc_meta *alloc_meta;
-       int i = 0;
 
        alloc_meta = kasan_get_alloc_meta(cache, object);
        if (!alloc_meta)
                return NULL;
 
-#ifdef CONFIG_KASAN_TAGS_IDENTIFY
-       for (i = 0; i < KASAN_NR_FREE_STACKS; i++) {
-               if (alloc_meta->free_pointer_tag[i] == tag)
-                       break;
-       }
-       if (i == KASAN_NR_FREE_STACKS)
-               i = alloc_meta->free_track_idx;
-#endif
-
-       return &alloc_meta->free_track[i];
+       return &alloc_meta->free_track;
 }