From 1f538e1f2d294cf8a9486fb1a7d4d4f0d16e2b01 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Mon, 5 Sep 2022 23:05:48 +0200 Subject: [PATCH] kasan: better identify bug types for tag-based modes Identify the bug type for the tag-based modes based on the stack trace entries found in the stack ring. If a free entry is found first (meaning that it was added last), mark the bug as use-after-free. If an alloc entry is found first, mark the bug as slab-out-of-bounds. Otherwise, assign the common bug type. This change returns the functionalify of the previously dropped CONFIG_KASAN_TAGS_IDENTIFY. Link: https://lkml.kernel.org/r/13ce7fa07d9d995caedd1439dfae4d51401842f2.1662411800.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Peter Collingbourne Signed-off-by: Andrew Morton --- mm/kasan/report_tags.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/mm/kasan/report_tags.c b/mm/kasan/report_tags.c index 57f73553..d351042 100644 --- a/mm/kasan/report_tags.c +++ b/mm/kasan/report_tags.c @@ -10,7 +10,7 @@ extern struct kasan_stack_ring stack_ring; -static const char *get_bug_type(struct kasan_report_info *info) +static const char *get_common_bug_type(struct kasan_report_info *info) { /* * If access_size is a negative number, then it has reason to be @@ -37,9 +37,8 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info) bool is_free; bool alloc_found = false, free_found = false; - info->bug_type = get_bug_type(info); - - if (!info->cache || !info->object) + if (!info->cache || !info->object) { + info->bug_type = get_common_bug_type(info); return; } @@ -84,6 +83,13 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info) info->free_track.pid = pid; info->free_track.stack = stack; free_found = true; + + /* + * If a free entry is found first, the bug is likely + * a use-after-free. + */ + if (!info->bug_type) + info->bug_type = "use-after-free"; } else { /* Second alloc of the same object. Give up. */ if (alloc_found) @@ -92,8 +98,19 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info) info->alloc_track.pid = pid; info->alloc_track.stack = stack; alloc_found = true; + + /* + * If an alloc entry is found first, the bug is likely + * an out-of-bounds. + */ + if (!info->bug_type) + info->bug_type = "slab-out-of-bounds"; } } write_unlock_irqrestore(&stack_ring.lock, flags); + + /* Assign the common bug type if no entries were found. */ + if (!info->bug_type) + info->bug_type = get_common_bug_type(info); } -- 2.7.4