From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>,
Evgeny Vereshchagin <evvers@ya.ru>
Subject: [PATCH v3 bpf-next 2/2] libbpf: fix BTF header parsing checks
Date: Fri, 22 Oct 2021 17:31:57 -0700 [thread overview]
Message-ID: <20211023003157.726961-2-andrii@kernel.org> (raw)
In-Reply-To: <20211023003157.726961-1-andrii@kernel.org>
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: 8a138aed4a80 ("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 05b945208815..ef924fc2c911 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -236,13 +236,19 @@ 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
prev parent reply other threads:[~2021-10-23 0:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-23 0:31 [PATCH v3 bpf-next 1/2] libbpf: fix overflow in BTF sanity checks Andrii Nakryiko
2021-10-23 0:31 ` Andrii Nakryiko [this message]
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