Commit f816938b authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Andrew Morton
Browse files

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: default avatarAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: default avatarAlexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7d88e4f7

mm/kasan/tags.c

+8 −2
Original line number Diff line number Diff line
@@ -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 @@ static void save_stack_info(struct kmem_cache *cache, void *object, 
	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 @@ static void save_stack_info(struct kmem_cache *cache, void *object, 
	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)