2018-07-01 21:00:26

by Guenter Roeck

Subject: [PATCH] staging: speakup: Replace strncpy with memcpy

gcc 8.1.0 generates the following warnings.

drivers/staging/speakup/kobjects.c: In function 'punc_store':
drivers/staging/speakup/kobjects.c:522:2: warning:
'strncpy' output truncated before terminating nul
copying as many bytes from a string as its length
drivers/staging/speakup/kobjects.c:504:6: note: length computed here

drivers/staging/speakup/kobjects.c: In function 'synth_store':
drivers/staging/speakup/kobjects.c:391:2: warning:
'strncpy' output truncated before terminating nul
copying as many bytes from a string as its length
drivers/staging/speakup/kobjects.c:388:8: note: length computed here

Using strncpy() is indeed less than perfect since the length of data to
be copied has already been determined with strlen(). Replace strncpy()
with memcpy() to address the warning and optimize the code a little.

Signed-off-by: Guenter Roeck <[email protected]>
---
drivers/staging/speakup/kobjects.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/speakup/kobjects.c b/drivers/staging/speakup/kobjects.c
index f1f90222186b..08f11cc17371 100644
--- a/drivers/staging/speakup/kobjects.c
+++ b/drivers/staging/speakup/kobjects.c
@@ -388,7 +388,7 @@ static ssize_t synth_store(struct kobject *kobj, struct kobj_attribute *attr,
len = strlen(buf);
if (len < 2 || len > 9)
return -EINVAL;
- strncpy(new_synth_name, buf, len);
+ memcpy(new_synth_name, buf, len);
if (new_synth_name[len - 1] == '\n')
len--;
new_synth_name[len] = '\0';
@@ -519,7 +519,7 @@ static ssize_t punc_store(struct kobject *kobj, struct kobj_attribute *attr,
return -EINVAL;
}

- strncpy(punc_buf, buf, x);
+ memcpy(punc_buf, buf, x);

while (x && punc_buf[x - 1] == '\n')
x--;
--
2.7.4

2018-07-01 22:12:23

by Samuel Thibault

Subject: Re: [PATCH] staging: speakup: Replace strncpy with memcpy

Guenter Roeck, le dim. 01 juil. 2018 13:57:24 -0700, a ecrit:
> gcc 8.1.0 generates the following warnings.
>
> drivers/staging/speakup/kobjects.c: In function 'punc_store':
> drivers/staging/speakup/kobjects.c:522:2: warning:
> 'strncpy' output truncated before terminating nul
> copying as many bytes from a string as its length
> drivers/staging/speakup/kobjects.c:504:6: note: length computed here
>
> drivers/staging/speakup/kobjects.c: In function 'synth_store':
> drivers/staging/speakup/kobjects.c:391:2: warning:
> 'strncpy' output truncated before terminating nul
> copying as many bytes from a string as its length
> drivers/staging/speakup/kobjects.c:388:8: note: length computed here
>
> Using strncpy() is indeed less than perfect since the length of data to
> be copied has already been determined with strlen(). Replace strncpy()
> with memcpy() to address the warning and optimize the code a little.
>
> Signed-off-by: Guenter Roeck <[email protected]>

Reviewed-by: Samuel Thibault <[email protected]>

> ---
> drivers/staging/speakup/kobjects.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/speakup/kobjects.c b/drivers/staging/speakup/kobjects.c
> index f1f90222186b..08f11cc17371 100644
> --- a/drivers/staging/speakup/kobjects.c
> +++ b/drivers/staging/speakup/kobjects.c
> @@ -388,7 +388,7 @@ static ssize_t synth_store(struct kobject *kobj, struct kobj_attribute *attr,
> len = strlen(buf);
> if (len < 2 || len > 9)
> return -EINVAL;
> - strncpy(new_synth_name, buf, len);
> + memcpy(new_synth_name, buf, len);
> if (new_synth_name[len - 1] == '\n')
> len--;
> new_synth_name[len] = '\0';
> @@ -519,7 +519,7 @@ static ssize_t punc_store(struct kobject *kobj, struct kobj_attribute *attr,
> return -EINVAL;
> }
>
> - strncpy(punc_buf, buf, x);
> + memcpy(punc_buf, buf, x);
>
> while (x && punc_buf[x - 1] == '\n')
> x--;
> --
> 2.7.4
>

--
Samuel
Tu as lu les docs. Tu es devenu un informaticien. Que tu le veuilles
ou non. Lire la doc, c'est le Premier et Unique Commandement de
l'informaticien.
-+- TP in: Guide du Linuxien pervers - "L'évangile selon St Thomas"