* [PATCH bpf] libbpf: fix BTF header parsing checks
@ 2021-10-21 5:46 Andrii Nakryiko
2021-10-21 22:15 ` Alexei Starovoitov
0 siblings, 1 reply; 3+ messages in thread
From: Andrii Nakryiko @ 2021-10-21 5:46 UTC (permalink / raw)
To: bpf, ast, daniel; +Cc: andrii, kernel-team, Evgeny Vereshchagin
Original code assumed fixed and correct BTF header length. That's not
always the case, though, so fix this bug with a proper additional check.
And use actual header length instead of sizeof(struct btf_header) in
sanity checks.
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Fixes: a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/lib/bpf/btf.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1ced31ecaf7f..aab7e4ece0a0 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -231,13 +231,19 @@ static int btf_parse_hdr(struct btf *btf)
}
btf_bswap_hdr(hdr);
} else if (hdr->magic != BTF_MAGIC) {
- pr_debug("Invalid BTF magic:%x\n", hdr->magic);
+ pr_debug("Invalid BTF magic: %x\n", hdr->magic);
return -EINVAL;
}
- meta_left = btf->raw_size - sizeof(*hdr);
+ if (btf->raw_size < hdr->hdr_len) {
+ pr_debug("BTF header len %u larger than data size %u\n",
+ hdr->hdr_len, btf->raw_size);
+ return -EINVAL;
+ }
+
+ meta_left = btf->raw_size - hdr->hdr_len;
if (meta_left < (long long)hdr->str_off + hdr->str_len) {
- pr_debug("Invalid BTF total size:%u\n", btf->raw_size);
+ pr_debug("Invalid BTF total size: %u\n", btf->raw_size);
return -EINVAL;
}
--
2.30.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf] libbpf: fix BTF header parsing checks
2021-10-21 5:46 [PATCH bpf] libbpf: fix BTF header parsing checks Andrii Nakryiko
@ 2021-10-21 22:15 ` Alexei Starovoitov
2021-10-21 22:28 ` Andrii Nakryiko
0 siblings, 1 reply; 3+ messages in thread
From: Alexei Starovoitov @ 2021-10-21 22:15 UTC (permalink / raw)
To: Andrii Nakryiko
Cc: bpf, Alexei Starovoitov, Daniel Borkmann, Kernel Team,
Evgeny Vereshchagin
On Wed, Oct 20, 2021 at 10:46 PM Andrii Nakryiko <andrii@kernel.org> wrote:
>
> Original code assumed fixed and correct BTF header length. That's not
> always the case, though, so fix this bug with a proper additional check.
> And use actual header length instead of sizeof(struct btf_header) in
> sanity checks.
>
> Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
> Fixes: a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
there is no such commit sha.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf] libbpf: fix BTF header parsing checks
2021-10-21 22:15 ` Alexei Starovoitov
@ 2021-10-21 22:28 ` Andrii Nakryiko
0 siblings, 0 replies; 3+ messages in thread
From: Andrii Nakryiko @ 2021-10-21 22:28 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Andrii Nakryiko, bpf, Alexei Starovoitov, Daniel Borkmann,
Kernel Team, Evgeny Vereshchagin
On Thu, Oct 21, 2021 at 3:16 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Wed, Oct 20, 2021 at 10:46 PM Andrii Nakryiko <andrii@kernel.org> wrote:
> >
> > Original code assumed fixed and correct BTF header length. That's not
> > always the case, though, so fix this bug with a proper additional check.
> > And use actual header length instead of sizeof(struct btf_header) in
> > sanity checks.
> >
> > Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
> > Fixes: a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
>
> there is no such commit sha.
Oops, seems like I lost the first digit, it should be:
8a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
^ permalink raw reply [flat|nested] 3+ messages in thread
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