From: Andrii Nakryiko <andrii@kernel.org>
Date: Sat, 23 Oct 2021 00:31:57 +0000 (-0700)
Subject: libbpf: Fix BTF header parsing checks
X-Git-Tag: v5.14.19~367
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7462b70c2cb95d68d0fd42f1c265fad7239768fe;p=thirdparty%2Fkernel%2Fstable.git

libbpf: Fix BTF header parsing checks

[ Upstream commit c825f5fee19caf301d9821cd79abaa734322de26 ]

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.

Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211023003157.726961-2-andrii@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 3e3ecac43ea9b..7ab9f702e72ac 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;
 	}