[PATCH bpf] bpf: use array_index_nospec in find_prog_type

[Daniel Borkmann]

Commit 9ef09e35e521 ("bpf: fix possible spectre-v1 in find_and_alloc_map()")
converted find_and_alloc_map() over to use array_index_nospec() to sanitize
map type that user space passes on map creation, and this patch does an
analogous conversion for progs in find_prog_type() as it's also passed from
user space when loading progs as attr->prog_type.

Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
Cc: Mark Rutland <mark.rutl...@arm.com>
---
 kernel/bpf/syscall.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 8f43448..016ef90 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -874,11 +874,17 @@ static const struct bpf_prog_ops * const bpf_prog_types[] 
= {
 
 static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
 {
-       if (type >= ARRAY_SIZE(bpf_prog_types) || !bpf_prog_types[type])
+       const struct bpf_prog_ops *ops;
+
+       if (type >= ARRAY_SIZE(bpf_prog_types))
+               return -EINVAL;
+       type = array_index_nospec(type, ARRAY_SIZE(bpf_prog_types));
+       ops = bpf_prog_types[type];
+       if (!ops)
                return -EINVAL;
 
        if (!bpf_prog_is_dev_bound(prog->aux))
-               prog->aux->ops = bpf_prog_types[type];
+               prog->aux->ops = ops;
        else
                prog->aux->ops = &bpf_offload_prog_ops;
        prog->type = type;
-- 
2.9.5