From f816938bff1f772ce7949e5747734be27ecf7f4d Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Mon, 20 Nov 2023 18:47:18 +0100 Subject: kasan: use stack_depot_put for tag-based modes Make tag-based KASAN modes evict stack traces from the stack depot once they are evicted from the stack ring. Internally, pass STACK_DEPOT_FLAG_GET to stack_depot_save_flags (via kasan_save_stack) to increment the refcount when saving a new entry to stack ring and call stack_depot_put when removing an entry from stack ring. Link: https://lkml.kernel.org/r/b4773e5c1b0b9df6826ec0b65c1923feadfa78e5.1700502145.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Alexander Potapenko Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Marco Elver Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/kasan/tags.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'mm/kasan') diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c index b6c017e670d8..739ae997463d 100644 --- a/mm/kasan/tags.c +++ b/mm/kasan/tags.c @@ -97,12 +97,13 @@ static void save_stack_info(struct kmem_cache *cache, void *object, gfp_t gfp_flags, bool is_free) { unsigned long flags; - depot_stack_handle_t stack; + depot_stack_handle_t stack, old_stack; u64 pos; struct kasan_stack_ring_entry *entry; void *old_ptr; - stack = kasan_save_stack(gfp_flags, STACK_DEPOT_FLAG_CAN_ALLOC); + stack = kasan_save_stack(gfp_flags, + STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET); /* * Prevent save_stack_info() from modifying stack ring @@ -121,6 +122,8 @@ next: if (!try_cmpxchg(&entry->ptr, &old_ptr, STACK_RING_BUSY_PTR)) goto next; /* Busy slot. */ + old_stack = entry->stack; + entry->size = cache->object_size; entry->pid = current->pid; entry->stack = stack; @@ -129,6 +132,9 @@ next: entry->ptr = object; read_unlock_irqrestore(&stack_ring.lock, flags); + + if (old_stack) + stack_depot_put(old_stack); } void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags) -- cgit v1.2.3