2022-12-03 07:11:40

by Yang Yang

Subject: [PATCH linux-next] accessibility: speakup: use strscpy() to instead of strncpy()

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]>
---
drivers/accessibility/speakup/kobjects.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/accessibility/speakup/kobjects.c b/drivers/accessibility/speakup/kobjects.c
index a7522d409802..273c076b661a 100644
--- a/drivers/accessibility/speakup/kobjects.c
+++ b/drivers/accessibility/speakup/kobjects.c
@@ -426,8 +426,7 @@ static ssize_t synth_direct_store(struct kobject *kobj,
spin_lock_irqsave(&speakup_info.spinlock, flags);
while (len > 0) {
bytes = min_t(size_t, len, 250);
- strncpy(tmp, ptr, bytes);
- tmp[bytes] = '\0';
+ strscpy(tmp, ptr, bytes);
string_unescape_any_inplace(tmp);
synth_printf("%s", tmp);
ptr += bytes;
--
2.15.2

2022-12-03 10:27:11

by Samuel Thibault

Subject: Re: [PATCH linux-next] accessibility: speakup: use strscpy() to instead of strncpy()

[email protected], le sam. 03 déc. 2022 14:21:28 +0800, a ecrit:
> 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]>
> ---
> drivers/accessibility/speakup/kobjects.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/accessibility/speakup/kobjects.c b/drivers/accessibility/speakup/kobjects.c
> index a7522d409802..273c076b661a 100644
> --- a/drivers/accessibility/speakup/kobjects.c
> +++ b/drivers/accessibility/speakup/kobjects.c
> @@ -426,8 +426,7 @@ static ssize_t synth_direct_store(struct kobject *kobj,
> spin_lock_irqsave(&speakup_info.spinlock, flags);
> while (len > 0) {
> bytes = min_t(size_t, len, 250);
> - strncpy(tmp, ptr, bytes);
> - tmp[bytes] = '\0';
> + strscpy(tmp, ptr, bytes);

This needs to be bytes+1, otherwise the trailing `\0` will be put at
bytes-1 instead of bytes as the original code does, thus eating one
character.

> string_unescape_any_inplace(tmp);
> synth_printf("%s", tmp);
> ptr += bytes;
> --
> 2.15.2
>