bpf: verifier: Use copy_array for jmp_history

Eliminate a couple needless kfree / kmalloc cycles by using
copy_array for jmp_history.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210429134656.122225-3-lmb@cloudflare.com

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a31afd0..380c8ad 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -926,16 +926,13 @@ static int copy_verifier_state(struct bpf_verifier_state *dst_state,
                               const struct bpf_verifier_state *src)
 {
        struct bpf_func_state *dst;
-       u32 jmp_sz = sizeof(struct bpf_idx_pair) * src->jmp_history_cnt;
        int i, err;
 
-       if (dst_state->jmp_history_cnt < src->jmp_history_cnt) {
-               kfree(dst_state->jmp_history);
-               dst_state->jmp_history = kmalloc(jmp_sz, GFP_USER);
-               if (!dst_state->jmp_history)
-                       return -ENOMEM;
-       }
-       memcpy(dst_state->jmp_history, src->jmp_history, jmp_sz);
+       dst_state->jmp_history = copy_array(dst_state->jmp_history, src->jmp_history,
+                                           src->jmp_history_cnt, sizeof(struct bpf_idx_pair),
+                                           GFP_USER);
+       if (!dst_state->jmp_history)
+               return -ENOMEM;
        dst_state->jmp_history_cnt = src->jmp_history_cnt;
 
        /* if dst has more stack frames then src frame, free them */