| Message ID | 20211021054623.3871933-1-andrii@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf] libbpf: fix BTF header parsing checks | expand |
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.
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")
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; }
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(-)