[PATCH 4.16 179/279] bpf: fix possible spectre-v1 in find_and_alloc_map()
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2018-06-18 08:25:26
Also in:
lkml, stable
4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Rutland <mark.rutland@arm.com> [ Upstream commit 9ef09e35e521bf0df5325cc9cffa726a8f5f3c1b ] It's possible for userspace to control attr->map_type. Sanitize it when using it as an array index to prevent an out-of-bounds value being used under speculation. Found by smatch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Dan Carpenter <redacted> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: netdev@vger.kernel.org Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <redacted> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/bpf/syscall.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c@@ -26,6 +26,7 @@ #include <linux/cred.h> #include <linux/timekeeping.h> #include <linux/ctype.h> +#include <linux/nospec.h> #define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PROG_ARRAY || \ (map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
@@ -102,12 +103,14 @@ const struct bpf_map_ops bpf_map_offload static struct bpf_map *find_and_alloc_map(union bpf_attr *attr) { const struct bpf_map_ops *ops; + u32 type = attr->map_type; struct bpf_map *map; int err; - if (attr->map_type >= ARRAY_SIZE(bpf_map_types)) + if (type >= ARRAY_SIZE(bpf_map_types)) return ERR_PTR(-EINVAL); - ops = bpf_map_types[attr->map_type]; + type = array_index_nospec(type, ARRAY_SIZE(bpf_map_types)); + ops = bpf_map_types[type]; if (!ops) return ERR_PTR(-EINVAL);
@@ -122,7 +125,7 @@ static struct bpf_map *find_and_alloc_ma if (IS_ERR(map)) return map; map->ops = ops; - map->map_type = attr->map_type; + map->map_type = type; return map; }