From: Xu Panda <[email protected]>
The implementation of strscpy() is more robust and safer.
That's now the recommended way to copy NUL-terminated strings.
Signed-off-by: Xu Panda <[email protected]>
Signed-off-by: Yang Yang <[email protected]>
---
kernel/trace/trace_events_synth.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 67592eed0be8..cd636edd045e 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -195,8 +195,7 @@ static int synth_field_string_size(char *type)
if (len == 0)
return 0; /* variable-length string */
- strncpy(buf, start, len);
- buf[len] = '\0';
+ strscpy(buf, start, len + 1);
err = kstrtouint(buf, 0, &size);
if (err)
--
2.15.2
On Mon, 9 Jan 2023 19:39:21 +0800 (CST)
<[email protected]> wrote:
> From: Xu Panda <[email protected]>
>
> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL-terminated strings.
This looks good to me.
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Thank you,
>
> Signed-off-by: Xu Panda <[email protected]>
> Signed-off-by: Yang Yang <[email protected]>
> ---
> kernel/trace/trace_events_synth.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> index 67592eed0be8..cd636edd045e 100644
> --- a/kernel/trace/trace_events_synth.c
> +++ b/kernel/trace/trace_events_synth.c
> @@ -195,8 +195,7 @@ static int synth_field_string_size(char *type)
> if (len == 0)
> return 0; /* variable-length string */
>
> - strncpy(buf, start, len);
> - buf[len] = '\0';
> + strscpy(buf, start, len + 1);
>
> err = kstrtouint(buf, 0, &size);
> if (err)
> --
> 2.15.2
--
Masami Hiramatsu (Google) <[email protected]>
On Mon, 9 Jan 2023 19:39:21 +0800 (CST)
<[email protected]> wrote:
> From: Xu Panda <[email protected]>
>
> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL-terminated strings.
But the string being copied is *not* NUL-terminated! And this change causes
a bug.
This is the 3rd patch I've seen that blindly converts strncpy() to
strscpy() and causes a bug in doing so. Not very safe if you ask me.
>
> Signed-off-by: Xu Panda <[email protected]>
> Signed-off-by: Yang Yang <[email protected]>
> ---
> kernel/trace/trace_events_synth.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> index 67592eed0be8..cd636edd045e 100644
> --- a/kernel/trace/trace_events_synth.c
> +++ b/kernel/trace/trace_events_synth.c
> @@ -195,8 +195,7 @@ static int synth_field_string_size(char *type)
> if (len == 0)
> return 0; /* variable-length string */
>
> - strncpy(buf, start, len);
> - buf[len] = '\0';
> + strscpy(buf, start, len + 1);
>
> err = kstrtouint(buf, 0, &size);
> if (err)
Here's the code being affected:
static int synth_field_string_size(char *type)
{
char buf[4], *end, *start;
unsigned int len;
int size, err;
start = strstr(type, "char[");
if (start == NULL)
return -EINVAL;
start += sizeof("char[") - 1;
end = strchr(type, ']');
if (!end || end < start || type + strlen(type) > end + 1)
return -EINVAL;
len = end - start;
if (len > 3)
return -EINVAL;
if (len == 0)
return 0; /* variable-length string */
strncpy(buf, start, len);
buf[len] = '\0';
And you are replacing the above two lines with just:
strscpy(buf, start, len + 1);
If you noticed, the string being placed into buf is:
"char[123]"
Where we want to copy that "123" into buf.
strscpy() expects the source to be nul terminated, or it will return -E2BIG.
So the above will *always* return -E2BIG *and* not end buf[] with '\0' as
if strscpy() returns -E2BIG, then buf[] is not guaranteed to be
NUL-terminated.
NACK!
-- Steve