[PATCH] trace-cmd: Fixed a potential problem with non-terminated string, returned by readlink()

[PATCH] trace-cmd: Fixed a potential problem with non-terminated string, returned by readlink()

[tz.stoyanov]

From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>

The buffer, returned by readlink() API, is not guaranteed to be a null terminated string.
Explicitly adding '\0' at the end of the buffer is recommended, to ensure the string is
null terminated and to avoid possible buffer overruns.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/trace-util.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
index 190cf74..7c74bae 100644
--- a/lib/trace-cmd/trace-util.c
+++ b/lib/trace-cmd/trace-util.c
@@ -1373,6 +1373,7 @@ static char *trace_util_get_source_plugins_dir(void)
 	ret = readlink("/proc/self/exe", path, PATH_MAX);
 	if (ret > PATH_MAX || ret < 0)
 		return NULL;
+	path[ret] = 0;
 
 	dirname(path);
 	p = strrchr(path, '/');
-- 
2.21.0

Re: [PATCH] trace-cmd: Fixed a potential problem with non-terminated string, returned by readlink()

[Yordan Karadzhov (VMware)]

On 3.07.19 г. 15:16 ч., tz.stoyanov@gmail.com wrote:
> From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
> 
> The buffer, returned by readlink() API, is not guaranteed to be a null terminated string.
> Explicitly adding '\0' at the end of the buffer is recommended, to ensure the string is
> null terminated and to avoid possible buffer overruns.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>   lib/trace-cmd/trace-util.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
> index 190cf74..7c74bae 100644
> --- a/lib/trace-cmd/trace-util.c
> +++ b/lib/trace-cmd/trace-util.c
> @@ -1373,6 +1373,7 @@ static char *trace_util_get_source_plugins_dir(void)
>   	ret = readlink("/proc/self/exe", path, PATH_MAX);
>   	if (ret > PATH_MAX || ret < 0)
>   		return NULL;
> +	path[ret] = 0;
>   
>   	dirname(path);
>   	p = strrchr(path, '/');
> 

Thanks!

Reviewed-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
Tested-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>