[PATCH v3 2/2] samples, selftests/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>
---
Changes in v3:
    - Added NULL check for samples/spintest_user.c

Changes in v2:
    - Added NULL check for selftests/bpf/prog_tests/get_stack_raw_tp.c

 samples/bpf/offwaketime_user.c                            | 5 +++++
 samples/bpf/sampleip_user.c                               | 5 +++++
 samples/bpf/spintest_user.c                               | 7 ++++++-
 samples/bpf/trace_event_user.c                            | 5 +++++
 tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c | 4 ++--
 5 files changed, 23 insertions(+), 3 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;
diff --git a/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c 
b/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
index d7bb5beb1c57..c2a0a9d5591b 100644
--- a/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
+++ b/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
@@ -39,7 +39,7 @@ static int get_stack_print_output(void *data, int size)
                } else {
                        for (i = 0; i < num_stack; i++) {
                                ks = ksym_search(raw_data[i]);
-                               if (strcmp(ks->name, nonjit_func) == 0) {
+                               if (ks && (strcmp(ks->name, nonjit_func) == 0)) 
{
                                        found = true;
                                        break;
                                }
@@ -56,7 +56,7 @@ static int get_stack_print_output(void *data, int size)
                } else {
                        for (i = 0; i < num_stack; i++) {
                                ks = ksym_search(e->kern_stack[i]);
-                               if (strcmp(ks->name, nonjit_func) == 0) {
+                               if (ks && (strcmp(ks->name, nonjit_func) == 0)) 
{
                                        good_kern_stack = true;
                                        break;
                                }
-- 
2.17.1