[PATCH AUTOSEL 4.19 030/100] samples: bpf: fix: seg fault with NULL pointer arg

[Sasha Levin]

From: "Daniel T. Lee" <danieltim...@gmail.com>

[ Upstream commit d59dd69d5576d699d7d3f5da0b4738c3a36d0133 ]

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 <danieltim...@gmail.com>
Acked-by: Song Liu <songliubrav...@fb.com>
Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 samples/bpf/bpf_load.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index 5061a2ec45646..176c04a454dc9 100644
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -59,7 +59,9 @@ 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;
-- 
2.20.1