netdev - [RFC PATCH v11 bpf-next 01/14] tools resolve_btfids: Add size check to get

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Message-Id: <20200809150302.686149-2-jolsa@kernel.org>
Date:   Sun,  9 Aug 2020 17:02:49 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Martin KaFai Lau <kafai@...com>,
        David Miller <davem@...hat.com>,
        John Fastabend <john.fastabend@...il.com>,
        Wenbo Zhang <ethercflow@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Brendan Gregg <bgregg@...flix.com>,
        Florent Revest <revest@...omium.org>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: [RFC PATCH v11 bpf-next 01/14] tools resolve_btfids: Add size check to get_id function

To make sure we don't crash on malformed symbols.

Acked-by: Andrii Nakryiko <andriin@...com>
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/bpf/resolve_btfids/main.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
index 52d883325a23..b83369887df6 100644
--- a/tools/bpf/resolve_btfids/main.c
+++ b/tools/bpf/resolve_btfids/main.c
@@ -199,9 +199,16 @@ static char *get_id(const char *prefix_end)
 	/*
 	 * __BTF_ID__func__vfs_truncate__0
 	 * prefix_end =  ^
+	 * pos        =    ^
 	 */
-	char *p, *id = strdup(prefix_end + sizeof("__") - 1);
+	int len = strlen(prefix_end);
+	int pos = sizeof("__") - 1;
+	char *p, *id;
 
+	if (pos >= len)
+		return NULL;
+
+	id = strdup(prefix_end + pos);
 	if (id) {
 		/*
 		 * __BTF_ID__func__vfs_truncate__0
-- 
2.25.4