| Message ID | 20230927-strncpy-drivers-misc-ti-st-st_kim-c-v1-1-29bbdeed1a2c@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | drivers: misc: ti-st: replace deprecated strncpy with strscpy | expand |
On Wed, Sep 27, 2023 at 06:17:34AM +0000, Justin Stitt wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings > [1] and as such we should prefer more robust and less ambiguous string > interfaces. > > We expect both `kim_data->dev_name` and `kim_gdata->dev_name` to be > NUL-terminated. > > `kim_data->dev_name` seems to not require NUL-padding. > > `kim_gdata` is already zero-allocated and as such does not require > NUL-padding: > | kim_gdata = kzalloc(sizeof(struct kim_data_s), GFP_KERNEL); > > Considering the above, a suitable replacement is `strscpy` [2] due to > the fact that it guarantees NUL-termination on the destination buffer > without unnecessarily NUL-padding. > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] > Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] > Link: https://github.com/KSPP/linux/issues/90 > Cc: linux-hardening@vger.kernel.org > Signed-off-by: Justin Stitt <justinstitt@google.com> > --- > Note: build-tested only. > --- > drivers/misc/ti-st/st_kim.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/misc/ti-st/st_kim.c b/drivers/misc/ti-st/st_kim.c > index fe682e0553b2..a034b5d8b585 100644 > --- a/drivers/misc/ti-st/st_kim.c > +++ b/drivers/misc/ti-st/st_kim.c > @@ -590,7 +590,7 @@ static ssize_t store_dev_name(struct device *dev, > { > struct kim_data_s *kim_data = dev_get_drvdata(dev); > pr_debug("storing dev name >%s<", buf); > - strncpy(kim_data->dev_name, buf, count); > + strscpy(kim_data->dev_name, buf, count); This is again the early truncation issue. This should use sizeof(kim_data->dev_name). "buf" will be %NUL terminated already. > pr_debug("stored dev name >%s<", kim_data->dev_name); > return count; > } > @@ -751,7 +751,8 @@ static int kim_probe(struct platform_device *pdev) > } > > /* copying platform data */ > - strncpy(kim_gdata->dev_name, pdata->dev_name, UART_DEV_NAME_LEN); > + strscpy(kim_gdata->dev_name, pdata->dev_name, > + sizeof(kim_gdata->dev_name)); This looks correct. > kim_gdata->flow_cntrl = pdata->flow_cntrl; > kim_gdata->baud_rate = pdata->baud_rate; > pr_info("sysfs entries created\n"); > > --- > base-commit: 6465e260f48790807eef06b583b38ca9789b6072 > change-id: 20230927-strncpy-drivers-misc-ti-st-st_kim-c-e1663a211a0c > > Best regards, > -- > Justin Stitt <justinstitt@google.com> >
diff --git a/drivers/misc/ti-st/st_kim.c b/drivers/misc/ti-st/st_kim.c index fe682e0553b2..a034b5d8b585 100644 --- a/drivers/misc/ti-st/st_kim.c +++ b/drivers/misc/ti-st/st_kim.c @@ -590,7 +590,7 @@ static ssize_t store_dev_name(struct device *dev, { struct kim_data_s *kim_data = dev_get_drvdata(dev); pr_debug("storing dev name >%s<", buf); - strncpy(kim_data->dev_name, buf, count); + strscpy(kim_data->dev_name, buf, count); pr_debug("stored dev name >%s<", kim_data->dev_name); return count; } @@ -751,7 +751,8 @@ static int kim_probe(struct platform_device *pdev) } /* copying platform data */ - strncpy(kim_gdata->dev_name, pdata->dev_name, UART_DEV_NAME_LEN); + strscpy(kim_gdata->dev_name, pdata->dev_name, + sizeof(kim_gdata->dev_name)); kim_gdata->flow_cntrl = pdata->flow_cntrl; kim_gdata->baud_rate = pdata->baud_rate; pr_info("sysfs entries created\n");
`strncpy` is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. We expect both `kim_data->dev_name` and `kim_gdata->dev_name` to be NUL-terminated. `kim_data->dev_name` seems to not require NUL-padding. `kim_gdata` is already zero-allocated and as such does not require NUL-padding: | kim_gdata = kzalloc(sizeof(struct kim_data_s), GFP_KERNEL); Considering the above, a suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on the destination buffer without unnecessarily NUL-padding. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt <justinstitt@google.com> --- Note: build-tested only. --- drivers/misc/ti-st/st_kim.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- base-commit: 6465e260f48790807eef06b583b38ca9789b6072 change-id: 20230927-strncpy-drivers-misc-ti-st-st_kim-c-e1663a211a0c Best regards, -- Justin Stitt <justinstitt@google.com>