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

[Andrii Nakryiko]

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

Signed-off-by: Andrii Nakryiko <andr...@fb.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