6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: YiFei Zhu zhuyifei@google.com
[ Upstream commit 43745d11bfd9683abdf08ad7a5cc403d6a9ffd15 ]
If cgroup_has_attached_progs queries an attach type not supported by the running kernel, due to the kernel being older than the bpftool build, it would encounter an -EINVAL from BPF_PROG_QUERY syscall.
Prior to commit 98b303c9bf05 ("bpftool: Query only cgroup-related attach types"), this EINVAL would be ignored by the function, allowing the function to only consider supported attach types. The commit changed so that, instead of querying all attach types, only attach types from the array `cgroup_attach_types` is queried. The assumption is that because these are only cgroup attach types, they should all be supported. Unfortunately this assumption may be false when the kernel is older than the bpftool build, where the attach types queried by bpftool is not yet implemented in the kernel. This would result in errors such as:
$ bpftool cgroup tree CgroupPath ID AttachType AttachFlags Name Error: can't query bpf programs attached to /sys/fs/cgroup: Invalid argument
This patch restores the logic of ignoring EINVAL from prior to that patch.
Fixes: 98b303c9bf05 ("bpftool: Query only cgroup-related attach types") Reported-by: Sagarika Sharma sharmasagarika@google.com Reported-by: Minh-Anh Nguyen minhanhdn@google.com Signed-off-by: YiFei Zhu zhuyifei@google.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Acked-by: Quentin Monnet qmo@kernel.org Link: https://lore.kernel.org/bpf/20250428211536.1651456-1-zhuyifei@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/bpf/bpftool/cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c index 9af426d432993..afab728468bf6 100644 --- a/tools/bpf/bpftool/cgroup.c +++ b/tools/bpf/bpftool/cgroup.c @@ -221,7 +221,7 @@ static int cgroup_has_attached_progs(int cgroup_fd) for (i = 0; i < ARRAY_SIZE(cgroup_attach_types); i++) { int count = count_attached_bpf_progs(cgroup_fd, cgroup_attach_types[i]);
- if (count < 0) + if (count < 0 && errno != EINVAL) return -1;
if (count > 0) {