From bb9a374dfa3a2f46581455ab66cd1d24c5e3d183 Mon Sep 17 00:00:00 2001 From: Vitaly Wool Date: Tue, 16 Jul 2019 16:25:48 -0700 Subject: mm/z3fold: don't try to use buddy slots after free As reported by Henry Burns: Running z3fold stress testing with address sanitization showed zhdr->slots was being used after it was freed. z3fold_free(z3fold_pool, handle) free_handle(handle) kmem_cache_free(pool->c_handle, zhdr->slots) release_z3fold_page_locked_list(kref) __release_z3fold_page(zhdr, true) zhdr_to_pool(zhdr) slots_to_pool(zhdr->slots) *BOOM* To fix this, add pointer to the pool back to z3fold_header and modify zhdr_to_pool to return zhdr->pool. Link: http://lkml.kernel.org/r/20190708134808.e89f3bfadd9f6ffd7eff9ba9@gmail.com Fixes: 7c2b8baa61fe ("mm/z3fold.c: add structure for buddy handles") Signed-off-by: Vitaly Wool Reported-by: Henry Burns Reviewed-by: Shakeel Butt Cc: Jonathan Adams Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/z3fold.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/z3fold.c b/mm/z3fold.c index dfcd69d08c1e..304f2883cdb9 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -101,6 +101,7 @@ struct z3fold_buddy_slots { * @refcount: reference count for the z3fold page * @work: work_struct for page layout optimization * @slots: pointer to the structure holding buddy slots + * @pool: pointer to the containing pool * @cpu: CPU which this page "belongs" to * @first_chunks: the size of the first buddy in chunks, 0 if free * @middle_chunks: the size of the middle buddy in chunks, 0 if free @@ -114,6 +115,7 @@ struct z3fold_header { struct kref refcount; struct work_struct work; struct z3fold_buddy_slots *slots; + struct z3fold_pool *pool; short cpu; unsigned short first_chunks; unsigned short middle_chunks; @@ -320,6 +322,7 @@ static struct z3fold_header *init_z3fold_page(struct page *page, zhdr->start_middle = 0; zhdr->cpu = -1; zhdr->slots = slots; + zhdr->pool = pool; INIT_LIST_HEAD(&zhdr->buddy); INIT_WORK(&zhdr->work, compact_page_work); return zhdr; @@ -426,7 +429,7 @@ static enum buddy handle_to_buddy(unsigned long handle) static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr) { - return slots_to_pool(zhdr->slots); + return zhdr->pool; } static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked) -- cgit v1.2.3-59-g8ed1b