| Message ID | 20231213164246.1021885-5-lee@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 0d12c1cca7883620b1888ce4b892a9ed27bf3682 |
| Headers | show |
| Series | usb: Replace {v}snprintf() variants with safer alternatives | expand |
Hi Lee, Thank you for the patch. On Wed, Dec 13, 2023 at 04:42:33PM +0000, Lee Jones wrote: > There is a general misunderstanding amongst engineers that {v}snprintf() > returns the length of the data *actually* encoded into the destination > array. However, as per the C99 standard {v}snprintf() really returns > the length of the data that *would have been* written if there were > enough space for it. This misunderstanding has led to buffer-overruns > in the past. It's generally considered safer to use the {v}scnprintf() > variants in their place (or even sprintf() in simple cases). So let's > do that. > > Link: https://lwn.net/Articles/69419/ > Link: https://github.com/KSPP/linux/issues/105 > Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > Cc: Daniel Scally <dan.scally@ideasonboard.com> > Cc: Andrzej Pietrasiewicz <andrzejtp2010@gmail.com> > Signed-off-by: Lee Jones <lee@kernel.org> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > --- > drivers/usb/gadget/function/uvc_configfs.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c > index 9bf0e985acfab..7e704b2bcfd1c 100644 > --- a/drivers/usb/gadget/function/uvc_configfs.c > +++ b/drivers/usb/gadget/function/uvc_configfs.c > @@ -3414,7 +3414,7 @@ static ssize_t f_uvc_opts_string_##cname##_show(struct config_item *item,\ > int result; \ > \ > mutex_lock(&opts->lock); \ > - result = snprintf(page, sizeof(opts->aname), "%s", opts->aname);\ > + result = scnprintf(page, sizeof(opts->aname), "%s", opts->aname);\ > mutex_unlock(&opts->lock); \ > \ > return result; \
diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c index 9bf0e985acfab..7e704b2bcfd1c 100644 --- a/drivers/usb/gadget/function/uvc_configfs.c +++ b/drivers/usb/gadget/function/uvc_configfs.c @@ -3414,7 +3414,7 @@ static ssize_t f_uvc_opts_string_##cname##_show(struct config_item *item,\ int result; \ \ mutex_lock(&opts->lock); \ - result = snprintf(page, sizeof(opts->aname), "%s", opts->aname);\ + result = scnprintf(page, sizeof(opts->aname), "%s", opts->aname);\ mutex_unlock(&opts->lock); \ \ return result; \
There is a general misunderstanding amongst engineers that {v}snprintf() returns the length of the data *actually* encoded into the destination array. However, as per the C99 standard {v}snprintf() really returns the length of the data that *would have been* written if there were enough space for it. This misunderstanding has led to buffer-overruns in the past. It's generally considered safer to use the {v}scnprintf() variants in their place (or even sprintf() in simple cases). So let's do that. Link: https://lwn.net/Articles/69419/ Link: https://github.com/KSPP/linux/issues/105 Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Daniel Scally <dan.scally@ideasonboard.com> Cc: Andrzej Pietrasiewicz <andrzejtp2010@gmail.com> Signed-off-by: Lee Jones <lee@kernel.org> --- drivers/usb/gadget/function/uvc_configfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)