The read-write lock semantics for stack_ring.lock are inverted: - save_stack_info() modifies stack ring entries but uses read_lock, which does not protect against concurrent writers and does not block readers from observing partial updates. - kasan_complete_mode_report_info() only reads the stack ring but uses write_lock_irqsave(), which prevents concurrent readers from walking the ring simultaneously. Swap the lock types to match their actual access patterns: - save_stack_info(): read_lock -> write_lock - kasan_complete_mode_report_info(): write_lock -> read_lock Fixes: 7bc0584e5d2a ("kasan: implement stack ring for tag-based modes") Signed-off-by: Xuewen Wang --- mm/kasan/report_tags.c | 4 ++-- mm/kasan/tags.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/kasan/report_tags.c b/mm/kasan/report_tags.c index d15f8f580e2c..62576b1470e1 100644 --- a/mm/kasan/report_tags.c +++ b/mm/kasan/report_tags.c @@ -39,7 +39,7 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info) return; } - write_lock_irqsave(&stack_ring.lock, flags); + read_lock_irqsave(&stack_ring.lock, flags); pos = atomic64_read(&stack_ring.pos); @@ -99,7 +99,7 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info) } } - write_unlock_irqrestore(&stack_ring.lock, flags); + read_unlock_irqrestore(&stack_ring.lock, flags); /* Assign the common bug type if no entries were found. */ if (!info->bug_type) diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c index d65d48b85f90..6aa09122f09e 100644 --- a/mm/kasan/tags.c +++ b/mm/kasan/tags.c @@ -110,7 +110,7 @@ static void save_stack_info(struct kmem_cache *cache, void *object, * Prevent save_stack_info() from modifying stack ring * when kasan_complete_mode_report_info() is walking it. */ - read_lock_irqsave(&stack_ring.lock, flags); + write_lock_irqsave(&stack_ring.lock, flags); next: pos = atomic64_fetch_add(1, &stack_ring.pos); @@ -131,7 +131,7 @@ static void save_stack_info(struct kmem_cache *cache, void *object, entry->ptr = object; - read_unlock_irqrestore(&stack_ring.lock, flags); + write_unlock_irqrestore(&stack_ring.lock, flags); if (old_stack) stack_depot_put(old_stack); -- 2.25.1