`strncpy` is deprecated for use on NUL-terminated destination strings [1].
We should prefer more robust and less ambiguous string interfaces.
Both `policy->last_governor` and `default_governor` are expected to be
NUL-terminated which is shown by their heavy usage with other string
apis like `strcmp`.
A suitable replacement is `strscpy` [2] due to the fact that it guarantees
NUL-termination on the destination buffer.
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: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Note: build-tested
---
drivers/cpufreq/cpufreq.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 50bbc969ffe5..3eb851a03fce 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1607,7 +1607,7 @@ static void __cpufreq_offline(unsigned int cpu, struct cpufreq_policy *policy)
}
if (has_target())
- strncpy(policy->last_governor, policy->governor->name,
+ strscpy(policy->last_governor, policy->governor->name,
CPUFREQ_NAME_LEN);
else
policy->last_policy = policy->policy;
@@ -2951,7 +2951,7 @@ static int __init cpufreq_core_init(void)
BUG_ON(!cpufreq_global_kobject);
if (!strlen(default_governor))
- strncpy(default_governor, gov->name, CPUFREQ_NAME_LEN);
+ strscpy(default_governor, gov->name, CPUFREQ_NAME_LEN);
return 0;
}
---
base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
change-id: 20230912-strncpy-drivers-cpufreq-cpufreq-c-1d800044b007
Best regards,
--
Justin Stitt <[email protected]>
On Wed, Sep 13, 2023 at 12:07:21AM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> We should prefer more robust and less ambiguous string interfaces.
>
> Both `policy->last_governor` and `default_governor` are expected to be
> NUL-terminated which is shown by their heavy usage with other string
> apis like `strcmp`.
>
> A suitable replacement is `strscpy` [2] due to the fact that it guarantees
> NUL-termination on the destination buffer.
>
> 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: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
All looks sensible to me.
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
On 13-09-23, 00:07, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> We should prefer more robust and less ambiguous string interfaces.
>
> Both `policy->last_governor` and `default_governor` are expected to be
> NUL-terminated which is shown by their heavy usage with other string
> apis like `strcmp`.
>
> A suitable replacement is `strscpy` [2] due to the fact that it guarantees
> NUL-termination on the destination buffer.
>
> 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: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> Note: build-tested
> ---
> drivers/cpufreq/cpufreq.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 50bbc969ffe5..3eb851a03fce 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1607,7 +1607,7 @@ static void __cpufreq_offline(unsigned int cpu, struct cpufreq_policy *policy)
> }
>
> if (has_target())
> - strncpy(policy->last_governor, policy->governor->name,
> + strscpy(policy->last_governor, policy->governor->name,
> CPUFREQ_NAME_LEN);
> else
> policy->last_policy = policy->policy;
> @@ -2951,7 +2951,7 @@ static int __init cpufreq_core_init(void)
> BUG_ON(!cpufreq_global_kobject);
>
> if (!strlen(default_governor))
> - strncpy(default_governor, gov->name, CPUFREQ_NAME_LEN);
> + strscpy(default_governor, gov->name, CPUFREQ_NAME_LEN);
>
> return 0;
> }
Acked-by: Viresh Kumar <[email protected]>
--
viresh
On Wed, 13 Sep 2023 00:07:21 +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> We should prefer more robust and less ambiguous string interfaces.
>
> Both `policy->last_governor` and `default_governor` are expected to be
> NUL-terminated which is shown by their heavy usage with other string
> apis like `strcmp`.
>
> [...]
Applied to for-next/hardening, thanks!
[1/1] cpufreq: refactor deprecated strncpy
https://git.kernel.org/kees/c/598b1b1c8f35
Take care,
--
Kees Cook