4.16-stable review patch. If anyone has any objections, please let me know.
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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 dan.carpenter@oracle.com 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 alexander.levin@microsoft.com 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; }