netdev - [PATCH v2 bpf-next 1/9] libbpf: fix detection of corrupted BPF instructions section

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Date:   Wed, 29 May 2019 10:36:03 -0700
From:   Andrii Nakryiko <andriin@...com>
To:     <andrii.nakryiko@...il.com>, <netdev@...r.kernel.org>,
        <bpf@...r.kernel.org>, <ast@...com>, <daniel@...earbox.net>,
        <kernel-team@...com>
CC:     Andrii Nakryiko <andriin@...com>
Subject: [PATCH v2 bpf-next 1/9] libbpf: fix detection of corrupted BPF instructions section

Ensure that size of a section w/ BPF instruction is exactly a multiple
of BPF instruction size.

Signed-off-by: Andrii Nakryiko <andriin@...com>
---
 tools/lib/bpf/libbpf.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ca4432f5b067..c6c9d632624a 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -349,8 +349,11 @@ static int
 bpf_program__init(void *data, size_t size, char *section_name, int idx,
 		  struct bpf_program *prog)
 {
-	if (size < sizeof(struct bpf_insn)) {
-		pr_warning("corrupted section '%s'\n", section_name);
+	const size_t bpf_insn_sz = sizeof(struct bpf_insn);
+
+	if (size == 0 || size % bpf_insn_sz) {
+		pr_warning("corrupted section '%s', size: %zu\n",
+			   section_name, size);
 		return -EINVAL;
 	}
 
@@ -376,9 +379,8 @@ bpf_program__init(void *data, size_t size, char *section_name, int idx,
 			   section_name);
 		goto errout;
 	}
-	prog->insns_cnt = size / sizeof(struct bpf_insn);
-	memcpy(prog->insns, data,
-	       prog->insns_cnt * sizeof(struct bpf_insn));
+	prog->insns_cnt = size / bpf_insn_sz;
+	memcpy(prog->insns, data, size);
 	prog->idx = idx;
 	prog->instances.fds = NULL;
 	prog->instances.nr = -1;
-- 
2.17.1