We currently allow to create perf link for program with
expected_attach_type == BPF_TRACE_KPROBE_MULTI.
This will cause crash when we call helpers like get_attach_cookie or
get_func_ip in such program, because it will call the kprobe_multi's
version (current->bpf_ctx context setup) of those helpers while it
expects perf_link's current->bpf_ctx context setup.
Making sure that we use BPF_TRACE_KPROBE_MULTI expected_attach_type
only for programs attaching through kprobe_multi link.
Fixes: ca74823c6e16 ("bpf: Add cookie support to programs attached with kprobe multi link")
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
kernel/bpf/syscall.c | 5 +++++
1 file changed, 5 insertions(+)
v2 changes:
- moved the check to bpf_prog_attach_check_attach_type [Andrii]
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 0c21d0d8efe4..129cc5c276c0 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3440,6 +3440,11 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
return prog->enforce_expected_attach_type &&
prog->expected_attach_type != attach_type ?
-EINVAL : 0;
+ case BPF_PROG_TYPE_KPROBE:
+ if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI &&
+ attach_type != BPF_TRACE_KPROBE_MULTI)
+ return -EINVAL;
+ fallthrough;
default:
return 0;
}
--
2.41.0
