samples, selftests/bpf: add NULL check for ksym_search

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 <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

4 files changed, 21 insertions, 1 deletions

diff --git a/samples/bpf/offwaketime_user.c b/samples/bpf/offwaketime_user.c
index f06063af9fcb..bb315ce1b866 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/spintest_user.c b/samples/bpf/spintest_user.c
index 8d3e9cfa1909..2556af2d9b3e 100644
--- a/samples/bpf/spintest_user.c
+++ b/samples/bpf/spintest_user.c
@@ -37,8 +37,13 @@ int main(int ac, char **argv)
                         bpf_map_lookup_elem(map_fd[0], &next_key, &value);
                         assert(next_key == value);
                         sym = ksym_search(value);
-                        printf(" %s", sym->name);
                         key = next_key;
+                        if (!sym) {
+                                printf("ksym not found. Is kallsyms loaded?\n");
+                                continue;
+                        }
+
+                        printf(" %s", sym->name);
                 }
                 if (key)
                         printf("\n");
diff --git a/samples/bpf/trace_event_user.c b/samples/bpf/trace_event_user.c
index d08046ab81f0..d4178f60e075 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;