This is a note to let you know that I've just added the patch titled
libbpf: Fix possible NULL pointer dereference when destroying skeleton
to the 5.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
libbpf-fix-possible-null-pointer-dereference-when-de.patch
and it can be found in the queue-5.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 329c4df614e7e72c021320f1bd868a92de8795ac
Author: Yafang Shao <laoar.shao@xxxxxxxxx>
Date: Sat Jan 8 13:47:39 2022 +0000
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 <laoar.shao@xxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20220108134739.32541-1-laoar.shao@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7f10dd501a52..fdb3536afa7d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11795,6 +11795,9 @@ 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)
