[PATCH v3 bpf-next 04/10] bpf: Protect probed address based on kptr_restrict setting

[Yafang Shao <laoar.shao@xxxxxxxxx>]

The probed address can be accessed by userspace through querying the task
file descriptor (fd). However, it is crucial to adhere to the kptr_restrict
setting and refrain from exposing the address if it is not permitted.

Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
---
 kernel/trace/trace_kprobe.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 59cda19..e4554db 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1551,7 +1551,10 @@ int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
 	} else {
 		*symbol = NULL;
 		*probe_offset = 0;
-		*probe_addr = (unsigned long)tk->rp.kp.addr;
+		if (kallsyms_show_value(current_cred()))
+			*probe_addr = (unsigned long)tk->rp.kp.addr;
+		else
+			*probe_addr = 0;
 	}
 	return 0;
 }
-- 
1.8.3.1