From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Subject: kasan: improve slab object description Changes slab object description from: Object at ffff880068388540, in cache kmalloc-128 size: 128 to: The buggy address belongs to the object at ffff880068388540 which belongs to the cache kmalloc-128 of size 128 The buggy address is located 123 bytes inside of 128-byte region [ffff880068388540, ffff8800683885c0) Makes it more explanatory and adds information about relative offset of the accessed address to the start of the object. Link: http://lkml.kernel.org/r/20170302134851.101218-7-andreyknvl@xxxxxxxxxx Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/kasan/report.c | 55 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 43 insertions(+), 12 deletions(-) diff -puN mm/kasan/report.c~kasan-improve-slab-object-description mm/kasan/report.c --- a/mm/kasan/report.c~kasan-improve-slab-object-description +++ a/mm/kasan/report.c @@ -198,18 +198,49 @@ static struct page *addr_to_page(const v return NULL; } -static void describe_object(struct kmem_cache *cache, void *object) +static void describe_object_addr(struct kmem_cache *cache, void *object, + const void *addr) { - struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); - - pr_err("Object at %p, in cache %s size: %d\n", object, cache->name, - cache->object_size); + unsigned long access_addr = (unsigned long)addr; + unsigned long object_addr = (unsigned long)object; + const char *rel_type; + int rel_bytes; + + pr_err("The buggy address belongs to the object at %p\n" + " which belongs to the cache %s of size %d\n", + object, cache->name, cache->object_size); - if (!(cache->flags & SLAB_KASAN)) + if (!addr) return; - print_track(&alloc_info->alloc_track, "Allocated"); - print_track(&alloc_info->free_track, "Freed"); + if (access_addr < object_addr) { + rel_type = "to the left"; + rel_bytes = object_addr - access_addr; + } else if (access_addr >= object_addr + cache->object_size) { + rel_type = "to the right"; + rel_bytes = access_addr - (object_addr + cache->object_size); + } else { + rel_type = "inside"; + rel_bytes = access_addr - object_addr; + } + + pr_err("The buggy address is located %d bytes %s of\n" + " %d-byte region [%p, %p)\n", + rel_bytes, rel_type, cache->object_size, (void *)object_addr, + (void *)(object_addr + cache->object_size)); +} + +static void describe_object(struct kmem_cache *cache, void *object, + const void *addr) +{ + struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); + + if (cache->flags & SLAB_KASAN) { + print_track(&alloc_info->alloc_track, "Allocated"); + print_track(&alloc_info->free_track, "Freed"); + } + + describe_object_addr(cache, object, addr); } void kasan_report_double_free(struct kmem_cache *cache, void *object, @@ -221,13 +252,13 @@ void kasan_report_double_free(struct kme pr_err("BUG: Double free or freeing an invalid pointer\n"); pr_err("Unexpected shadow byte: 0x%hhX\n", shadow); dump_stack(); - describe_object(cache, object); + describe_object(cache, object, NULL); kasan_end_report(&flags); } static void print_address_description(struct kasan_access_info *info) { - const void *addr = info->access_addr; + void *addr = (void *)info->access_addr; struct page *page = addr_to_page(addr); if (page) @@ -237,9 +268,9 @@ static void print_address_description(st if (page && PageSlab(page)) { struct kmem_cache *cache = page->slab_cache; - void *object = nearest_obj(cache, page, (void *)addr); + void *object = nearest_obj(cache, page, addr); - describe_object(cache, object); + describe_object(cache, object, addr); } if (kernel_or_module_addr(addr)) { _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
