From db429f16e0b472292000fd53b63ebd7221a9856e Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 3 May 2017 14:56:34 -0700 Subject: [PATCH] kasan: simplify address description logic Simplify logic for describing a memory address. Add addr_to_page() helper function. Makes the code easier to follow. Link: http://lkml.kernel.org/r/20170302134851.101218-5-andreyknvl@google.com Signed-off-by: Andrey Konovalov Acked-by: Dmitry Vyukov Cc: Andrey Ryabinin Cc: Alexander Potapenko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/kasan/report.c | 37 +++++++++++++++++++++---------------- 1 file changed, 21 insertions(+), 16 deletions(-) diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 7d24363..a82d689 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -190,11 +190,18 @@ static void print_track(struct kasan_track *track, const char *prefix) } } -static void kasan_object_err(struct kmem_cache *cache, void *object) +static struct page *addr_to_page(const void *addr) +{ + if ((addr >= (void *)PAGE_OFFSET) && + (addr < high_memory)) + return virt_to_head_page(addr); + return NULL; +} + +static void describe_object(struct kmem_cache *cache, void *object) { struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); - dump_stack(); pr_err("Object at %p, in cache %s size: %d\n", object, cache->name, cache->object_size); @@ -213,34 +220,32 @@ void kasan_report_double_free(struct kmem_cache *cache, void *object, kasan_start_report(&flags); pr_err("BUG: Double free or freeing an invalid pointer\n"); pr_err("Unexpected shadow byte: 0x%hhX\n", shadow); - kasan_object_err(cache, object); + dump_stack(); + describe_object(cache, object); kasan_end_report(&flags); } static void print_address_description(struct kasan_access_info *info) { const void *addr = info->access_addr; + struct page *page = addr_to_page(addr); - if ((addr >= (void *)PAGE_OFFSET) && - (addr < high_memory)) { - struct page *page = virt_to_head_page(addr); - - if (PageSlab(page)) { - void *object; - struct kmem_cache *cache = page->slab_cache; - object = nearest_obj(cache, page, - (void *)info->access_addr); - kasan_object_err(cache, object); - return; - } + if (page) dump_page(page, "kasan: bad access detected"); + + dump_stack(); + + if (page && PageSlab(page)) { + struct kmem_cache *cache = page->slab_cache; + void *object = nearest_obj(cache, page, (void *)addr); + + describe_object(cache, object); } if (kernel_or_module_addr(addr)) { if (!init_task_stack_addr(addr)) pr_err("Address belongs to variable %pS\n", addr); } - dump_stack(); } static bool row_is_guilty(const void *row, const void *guilty) -- 2.7.4