samples: bpf: fix: seg fault with NULL pointer arg

When NULL pointer accidentally passed to write_kprobe_events,
due to strlen(NULL), segmentation fault happens.
Changed code returns -1 to deal with this situation.

Bug issued with Smatch, static analysis.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index 434ea34a59549d4e6f57698850443f2c50d6354a..eae7b635343d13182a4d458d3280464f6ffee4ca 100644 (file)
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -58,7 +58,9 @@ static int write_kprobe_events(const char *val)
 {
        int fd, ret, flags;
 
-       if ((val != NULL) && (val[0] == '\0'))
+       if (val == NULL)
+               return -1;
+       else if (val[0] == '\0')
                flags = O_WRONLY | O_TRUNC;
        else
                flags = O_WRONLY | O_APPEND;