diff options
Diffstat (limited to 'mm/kasan/report_tags.c')
-rw-r--r-- | mm/kasan/report_tags.c | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/mm/kasan/report_tags.c b/mm/kasan/report_tags.c index 5cbac2cdb177..1b78136542bb 100644 --- a/mm/kasan/report_tags.c +++ b/mm/kasan/report_tags.c @@ -4,8 +4,12 @@ * Copyright (c) 2020 Google, Inc. */ +#include <linux/atomic.h> + #include "kasan.h" +extern struct kasan_stack_ring stack_ring; + static const char *get_bug_type(struct kasan_report_info *info) { /* @@ -24,5 +28,72 @@ static const char *get_bug_type(struct kasan_report_info *info) void kasan_complete_mode_report_info(struct kasan_report_info *info) { + unsigned long flags; + u64 pos; + struct kasan_stack_ring_entry *entry; + void *ptr; + u32 pid; + depot_stack_handle_t stack; + bool is_free; + bool alloc_found = false, free_found = false; + info->bug_type = get_bug_type(info); + + if (!info->cache || !info->object) + return; + } + + write_lock_irqsave(&stack_ring.lock, flags); + + pos = atomic64_read(&stack_ring.pos); + + /* + * The loop below tries to find stack ring entries relevant to the + * buggy object. This is a best-effort process. + * + * First, another object with the same tag can be allocated in place of + * the buggy object. Also, since the number of entries is limited, the + * entries relevant to the buggy object can be overwritten. + */ + + for (u64 i = pos - 1; i != pos - 1 - KASAN_STACK_RING_SIZE; i--) { + if (alloc_found && free_found) + break; + + entry = &stack_ring.entries[i % KASAN_STACK_RING_SIZE]; + + /* Paired with smp_store_release() in save_stack_info(). */ + ptr = (void *)smp_load_acquire(&entry->ptr); + + if (kasan_reset_tag(ptr) != info->object || + get_tag(ptr) != get_tag(info->access_addr)) + continue; + + pid = READ_ONCE(entry->pid); + stack = READ_ONCE(entry->stack); + is_free = READ_ONCE(entry->is_free); + + if (is_free) { + /* + * Second free of the same object. + * Give up on trying to find the alloc entry. + */ + if (free_found) + break; + + info->free_track.pid = pid; + info->free_track.stack = stack; + free_found = true; + } else { + /* Second alloc of the same object. Give up. */ + if (alloc_found) + break; + + info->alloc_track.pid = pid; + info->alloc_track.stack = stack; + alloc_found = true; + } + } + + write_unlock_irqrestore(&stack_ring.lock, flags); } |