From: "Daniel T. Lee" <danieltimlee@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
Martin KaFai Lau <kafai@fb.com>
Subject: [PATCH] tools: bpftool: fix struct_ops command invalid pointer free
Date: Fri, 10 Apr 2020 11:06:12 +0900 [thread overview]
Message-ID: <20200410020612.2930667-1-danieltimlee@gmail.com> (raw)
From commit 65c93628599d ("bpftool: Add struct_ops support"),
a new type of command struct_ops has been added.
This command requires kernel CONFIG_DEBUG_INFO_BTF=y, and for retrieving
btf info, get_btf_vmlinux() is used.
When running this command on kernel without BTF debug info, this will
lead to 'btf_vmlinux' variable contains invalid(error) pointer. And by
this, btf_free() causes a segfault when executing 'bpftool struct_ops'.
This commit adds pointer validation with IS_ERR not to free invalid
pointer, and this will fix the segfault issue.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
---
tools/bpf/bpftool/struct_ops.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/struct_ops.c b/tools/bpf/bpftool/struct_ops.c
index 2a7befbd11ad..0fe0d584c57e 100644
--- a/tools/bpf/bpftool/struct_ops.c
+++ b/tools/bpf/bpftool/struct_ops.c
@@ -591,6 +591,8 @@ int do_struct_ops(int argc, char **argv)
err = cmd_select(cmds, argc, argv, do_help);
- btf__free(btf_vmlinux);
+ if (!IS_ERR(btf_vmlinux))
+ btf__free(btf_vmlinux);
+
return err;
}
--
2.26.0
next reply other threads:[~2020-04-10 2:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-10 2:06 Daniel T. Lee [this message]
2020-04-10 5:03 ` [PATCH] tools: bpftool: fix struct_ops command invalid pointer free Martin KaFai Lau
2020-04-10 5:34 ` Daniel T. Lee
2020-04-14 19:44 ` Daniel Borkmann
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