From 8e1cbdee2172100329897930e16fa240a000951c Mon Sep 17 00:00:00 2001
From: "Daniel T. Lee" <danieltimlee@gmail.com>
Date: Thu, 7 Nov 2019 17:32:58 +0800
Subject: [PATCH] samples: bpf: fix: seg fault with NULL pointer arg

[ 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 <danieltimlee@gmail.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 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 5061a2ec4564..176c04a454dc 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;
-- 
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