| Message ID | 20231020-strncpy-drivers-power-supply-surface_charger-c-v1-1-93ddbf668e10@google.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | power: supply: surface-charger: replace deprecated strncpy with strscpy | expand |
On Fri, 20 Oct 2023 19:46:11 +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 ac->name to be NUL-terminated based on its usage with format > strings: > > [...] Applied, thanks! [1/1] power: supply: surface-charger: replace deprecated strncpy with strscpy commit: afc88dfda013970bb1e214b331e99adca2f98312 Best regards,
On 10/20/23 21:46, 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 ac->name to be NUL-terminated based on its usage with format > strings: > > surface_charger.c: > 190: ac->psy_desc.name = ac->name; > > ... > > power_supply_core.c: > 174: dev_dbg(&psy->dev, "%s: Found supply : %s\n", > 175: psy->desc->name, epsy->desc->name); > > Moreover, NUL-padding is not required as ac is already zero-allocated > before being passed to spwr_ac_init(): > > surface_charger.c: > 240: ac = devm_kzalloc(&sdev->dev, sizeof(*ac), GFP_KERNEL); > 241: if (!ac) > 242: return -ENOMEM; > 243: > 244: spwr_ac_init(ac, sdev, p->registry, p->name); > > ... this means any future NUL-byte assignments (like the ones that > strncpy() does) are redundant. > > 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. > > Let's also opt for the more idiomatic strscpy() usage of: > (dest, src, sizeof(dest)) > > 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> Thanks! Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com> Tested-by: Maximilian Luz <luzmaximilian@gmail.com> > --- > Note: build-tested only. > > Found with: $ rg "strncpy\(" > --- > drivers/power/supply/surface_charger.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/power/supply/surface_charger.c b/drivers/power/supply/surface_charger.c > index cabdd8da12d0..7a6c62d6f883 100644 > --- a/drivers/power/supply/surface_charger.c > +++ b/drivers/power/supply/surface_charger.c > @@ -175,7 +175,7 @@ static void spwr_ac_init(struct spwr_ac_device *ac, struct ssam_device *sdev, > struct ssam_event_registry registry, const char *name) > { > mutex_init(&ac->lock); > - strncpy(ac->name, name, ARRAY_SIZE(ac->name) - 1); > + strscpy(ac->name, name, sizeof(ac->name)); > > ac->sdev = sdev; > > > --- > base-commit: bb55d7f7f7445abcc8db50e6a65d4315e79f75c7 > change-id: 20231020-strncpy-drivers-power-supply-surface_charger-c-466920fb1f48 > > Best regards, > -- > Justin Stitt <justinstitt@google.com> >
diff --git a/drivers/power/supply/surface_charger.c b/drivers/power/supply/surface_charger.c index cabdd8da12d0..7a6c62d6f883 100644 --- a/drivers/power/supply/surface_charger.c +++ b/drivers/power/supply/surface_charger.c @@ -175,7 +175,7 @@ static void spwr_ac_init(struct spwr_ac_device *ac, struct ssam_device *sdev, struct ssam_event_registry registry, const char *name) { mutex_init(&ac->lock); - strncpy(ac->name, name, ARRAY_SIZE(ac->name) - 1); + strscpy(ac->name, name, sizeof(ac->name)); ac->sdev = sdev;
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 ac->name to be NUL-terminated based on its usage with format strings: surface_charger.c: 190: ac->psy_desc.name = ac->name; ... power_supply_core.c: 174: dev_dbg(&psy->dev, "%s: Found supply : %s\n", 175: psy->desc->name, epsy->desc->name); Moreover, NUL-padding is not required as ac is already zero-allocated before being passed to spwr_ac_init(): surface_charger.c: 240: ac = devm_kzalloc(&sdev->dev, sizeof(*ac), GFP_KERNEL); 241: if (!ac) 242: return -ENOMEM; 243: 244: spwr_ac_init(ac, sdev, p->registry, p->name); ... this means any future NUL-byte assignments (like the ones that strncpy() does) are redundant. 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. Let's also opt for the more idiomatic strscpy() usage of: (dest, src, sizeof(dest)) 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. Found with: $ rg "strncpy\(" --- drivers/power/supply/surface_charger.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- base-commit: bb55d7f7f7445abcc8db50e6a65d4315e79f75c7 change-id: 20231020-strncpy-drivers-power-supply-surface_charger-c-466920fb1f48 Best regards, -- Justin Stitt <justinstitt@google.com>