netdev - [PATCH bpf-next 2/3] bpf: verifier: use copy_array for jmp

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Message-Id: <20210429134656.122225-3-lmb@cloudflare.com>
Date:   Thu, 29 Apr 2021 14:46:55 +0100
From:   Lorenz Bauer <lmb@...udflare.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>
Cc:     kernel-team@...udflare.com, Lorenz Bauer <lmb@...udflare.com>,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next 2/3] 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@...udflare.com>
---
 kernel/bpf/verifier.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 67d914b26a39..2b9623ac9288 100644
--- 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 */
-- 
2.27.0