[PATCH 2/2] samples/bpf: add NULL check for ksym_search

[Daniel T. Lee]

Since, ksym_search added with verification logic for symbols existence,
it could return NULL when the kernel symbols are not loaded.

This commit will add NULL check logic after ksym_search.

Signed-off-by: Daniel T. Lee <danieltim...@gmail.com>
---
 samples/bpf/offwaketime_user.c | 5 +++++
 samples/bpf/sampleip_user.c    | 5 +++++
 samples/bpf/trace_event_user.c | 5 +++++
 3 files changed, 15 insertions(+)

diff --git a/samples/bpf/offwaketime_user.c b/samples/bpf/offwaketime_user.c
index f06063af9fcb..52e29467a509 100644
--- a/samples/bpf/offwaketime_user.c
+++ b/samples/bpf/offwaketime_user.c
@@ -28,6 +28,11 @@ static void print_ksym(__u64 addr)
        if (!addr)
                return;
        sym = ksym_search(addr);
+       if (!sym){
+               printf("ksym not found. Is kallsyms loaded?\n");
+               return;
+       }
+
        if (PRINT_RAW_ADDR)
                printf("%s/%llx;", sym->name, addr);
        else
diff --git a/samples/bpf/sampleip_user.c b/samples/bpf/sampleip_user.c
index 216c7ecbbbe9..23b90a45c802 100644
--- a/samples/bpf/sampleip_user.c
+++ b/samples/bpf/sampleip_user.c
@@ -109,6 +109,11 @@ static void print_ip_map(int fd)
        for (i = 0; i < max; i++) {
                if (counts[i].ip > PAGE_OFFSET) {
                        sym = ksym_search(counts[i].ip);
+                       if (!sym) {
+                               printf("ksym not found. Is kallsyms loaded?\n");
+                               continue;
+                       }
+
                        printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name,
                               counts[i].count);
                } else {
diff --git a/samples/bpf/trace_event_user.c b/samples/bpf/trace_event_user.c
index d08046ab81f0..bc8e6afdae6d 100644
--- a/samples/bpf/trace_event_user.c
+++ b/samples/bpf/trace_event_user.c
@@ -34,6 +34,11 @@ static void print_ksym(__u64 addr)
        if (!addr)
                return;
        sym = ksym_search(addr);
+       if (!sym){
+               printf("ksym not found. Is kallsyms loaded?\n");
+               return;
+       }
+
        printf("%s;", sym->name);
        if (!strcmp(sym->name, "sys_read"))
                sys_read_seen = true;
-- 
2.17.1