From b385ebe91ae917677ae8cdd3240828155248ff0c Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Sat, 8 Jan 2022 13:47:39 +0000 Subject: libbpf: Fix possible NULL pointer dereference when destroying skeleton [ Upstream commit a32ea51a3f17ce6524c9fc19d311e708331c8b5f ] When I checked the code in skeleton header file generated with my own bpf prog, I found there may be possible NULL pointer dereference when destroying skeleton. Then I checked the in-tree bpf progs, finding that is a common issue. Let's take the generated samples/bpf/xdp_redirect_cpu.skel.h for example. Below is the generated code in xdp_redirect_cpu__create_skeleton(): xdp_redirect_cpu__create_skeleton struct bpf_object_skeleton *s; s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s)); if (!s) goto error; ... error: bpf_object__destroy_skeleton(s); return -ENOMEM; After goto error, the NULL 's' will be deferenced in bpf_object__destroy_skeleton(). We can simply fix this issue by just adding a NULL check in bpf_object__destroy_skeleton(). Fixes: d66562fba1ce ("libbpf: Add BPF object skeleton support") Signed-off-by: Yafang Shao Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220108134739.32541-1-laoar.shao@gmail.com Signed-off-by: Sasha Levin --- tools/lib/bpf/libbpf.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'tools') diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0ad29203cbfb..693e14799fb9 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10809,6 +10809,9 @@ void bpf_object__detach_skeleton(struct bpf_object_skeleton *s) void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s) { + if (!s) + return; + if (s->progs) bpf_object__detach_skeleton(s); if (s->obj) -- cgit v1.2.3