From ff1c08e1f74b6864854c39be48aa799a6a2e4d2b Mon Sep 17 00:00:00 2001 From: =?utf8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Tue, 29 Oct 2019 16:43:07 +0100 Subject: [PATCH] bpf: Change size to u64 for bpf_map_{area_alloc, charge_init}() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The functions bpf_map_area_alloc() and bpf_map_charge_init() prior this commit passed the size parameter as size_t. In this commit this is changed to u64. All users of these functions avoid size_t overflows on 32-bit systems, by explicitly using u64 when calculating the allocation size and memory charge cost. However, since the result was narrowed by the size_t when passing size and cost to the functions, the overflow handling was in vain. Instead of changing all call sites to size_t and handle overflow at the call site, the parameter is changed to u64 and checked in the functions above. Fixes: d407bd25a204 ("bpf: don't trigger OOM killer under pressure with map alloc") Fixes: c85d69135a91 ("bpf: move memory size checks to bpf_map_charge_init()") Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Reviewed-by: Jakub Kicinski Link: https://lore.kernel.org/bpf/20191029154307.23053-1-bjorn.topel@gmail.com --- include/linux/bpf.h | 4 ++-- kernel/bpf/syscall.c | 7 +++++-- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 5b9d223..3bf3835 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -656,11 +656,11 @@ void bpf_map_put_with_uref(struct bpf_map *map); void bpf_map_put(struct bpf_map *map); int bpf_map_charge_memlock(struct bpf_map *map, u32 pages); void bpf_map_uncharge_memlock(struct bpf_map *map, u32 pages); -int bpf_map_charge_init(struct bpf_map_memory *mem, size_t size); +int bpf_map_charge_init(struct bpf_map_memory *mem, u64 size); void bpf_map_charge_finish(struct bpf_map_memory *mem); void bpf_map_charge_move(struct bpf_map_memory *dst, struct bpf_map_memory *src); -void *bpf_map_area_alloc(size_t size, int numa_node); +void *bpf_map_area_alloc(u64 size, int numa_node); void bpf_map_area_free(void *base); void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0937719..ace1cfa 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -126,7 +126,7 @@ static struct bpf_map *find_and_alloc_map(union bpf_attr *attr) return map; } -void *bpf_map_area_alloc(size_t size, int numa_node) +void *bpf_map_area_alloc(u64 size, int numa_node) { /* We really just want to fail instead of triggering OOM killer * under memory pressure, therefore we set __GFP_NORETRY to kmalloc, @@ -141,6 +141,9 @@ void *bpf_map_area_alloc(size_t size, int numa_node) const gfp_t flags = __GFP_NOWARN | __GFP_ZERO; void *area; + if (size >= SIZE_MAX) + return NULL; + if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) { area = kmalloc_node(size, GFP_USER | __GFP_NORETRY | flags, numa_node); @@ -197,7 +200,7 @@ static void bpf_uncharge_memlock(struct user_struct *user, u32 pages) atomic_long_sub(pages, &user->locked_vm); } -int bpf_map_charge_init(struct bpf_map_memory *mem, size_t size) +int bpf_map_charge_init(struct bpf_map_memory *mem, u64 size) { u32 pages = round_up(size, PAGE_SIZE) >> PAGE_SHIFT; struct user_struct *user; -- 2.7.4