[PATCH bpf 1/2] bpf: Add override check to kprobe multi link attach

[Jiri Olsa <jolsa@kernel.org>]

Currently the multi_kprobe link attach does not check error
injection list for programs with bpf_override_return helper
and allows them to attach anywhere. Adding the missing check.

Cc: stable@vger.kernel.org
Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/trace/bpf_trace.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index a7264b2c17ad..c1c1af63ced2 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2853,6 +2853,17 @@ static int get_modules_for_addrs(struct module ***mods, unsigned long *addrs, u3
 	return arr.mods_cnt;
 }
 
+static int addrs_check_error_injection_list(unsigned long *addrs, u32 cnt)
+{
+	u32 i;
+
+	for (i = 0; i < cnt; i++) {
+		if (!within_error_injection_list(addrs[i]))
+			return -EINVAL;
+	}
+	return 0;
+}
+
 int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 {
 	struct bpf_kprobe_multi_link *link = NULL;
@@ -2930,6 +2941,11 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 			goto error;
 	}
 
+	if (prog->kprobe_override && addrs_check_error_injection_list(addrs, cnt)) {
+		err = -EINVAL;
+		goto error;
+	}
+
 	link = kzalloc(sizeof(*link), GFP_KERNEL);
 	if (!link) {
 		err = -ENOMEM;
-- 
2.41.0