* [PATCH] samples: bpf: fix: seg fault with NULL pointer arg
@ 2018-12-01 21:06 Daniel T. Lee
2018-12-03 7:52 ` Song Liu
0 siblings, 1 reply; 2+ messages in thread
From: Daniel T. Lee @ 2018-12-01 21:06 UTC (permalink / raw)
To: Daniel Borkmann, Alexei Starovoitov; +Cc: netdev
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>
---
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 434ea34a5954..c670bd2200d2 100644
--- 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 != NULL) && (val[0] == '\0'))
flags = O_WRONLY | O_TRUNC;
else
flags = O_WRONLY | O_APPEND;
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] samples: bpf: fix: seg fault with NULL pointer arg
2018-12-01 21:06 [PATCH] samples: bpf: fix: seg fault with NULL pointer arg Daniel T. Lee
@ 2018-12-03 7:52 ` Song Liu
0 siblings, 0 replies; 2+ messages in thread
From: Song Liu @ 2018-12-03 7:52 UTC (permalink / raw)
To: danieltimlee; +Cc: Daniel Borkmann, Alexei Starovoitov, Networking
On Sat, Dec 1, 2018 at 1:07 PM Daniel T. Lee <danieltimlee@gmail.com> wrote:
>
> 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>
> ---
> 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 434ea34a5954..c670bd2200d2 100644
> --- 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 != NULL) && (val[0] == '\0'))
We only need
+ else if (val[0] == '\0')
right?
Thanks,
Song
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