2018-08-21 12:27:34

by Anders Roxell

Subject: [PATCH] cpupower: remove stringop-truncation waring

The strncpy doesn't null terminate the string because the size is too
short by one byte.

parse.c: In function ‘prepare_default_config’:
parse.c:148:2: warning: ‘strncpy’ output truncated before terminating
nul copying 8 bytes from a string of the same length
[-Wstringop-truncation]
strncpy(config->governor, "ondemand", 8);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Passing the length of the input argument to strncpy() is almost always
wrong and provides no extra benefit over strcpy(), and since 'ondemand'
fits within 15 bytes" and it null terminates the string its safe to use
strcpy().

Fixes: 7fe2f6399a84 ("cpupowerutils - cpufrequtils extended with quite some features")
Signed-off-by: Anders Roxell <[email protected]>
---
tools/power/cpupower/bench/parse.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/power/cpupower/bench/parse.c b/tools/power/cpupower/bench/parse.c
index 9ba8a44ad2a7..91b5b768ffd2 100644
--- a/tools/power/cpupower/bench/parse.c
+++ b/tools/power/cpupower/bench/parse.c
@@ -145,7 +145,7 @@ struct config *prepare_default_config()
config->cpu = 0;
config->prio = SCHED_HIGH;
config->verbose = 0;
- strncpy(config->governor, "ondemand", 8);
+ strcpy(config->governor, "ondemand");

config->output = stdout;

--
2.18.0

2018-08-27 17:49:09

by Shuah Khan

Subject: Re: [PATCH] cpupower: remove stringop-truncation waring

On 08/21/2018 06:02 AM, Anders Roxell wrote:
> The strncpy doesn't null terminate the string because the size is too
> short by one byte.
>
> parse.c: In function ‘prepare_default_config’:
> parse.c:148:2: warning: ‘strncpy’ output truncated before terminating
> nul copying 8 bytes from a string of the same length
> [-Wstringop-truncation]
> strncpy(config->governor, "ondemand", 8);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Passing the length of the input argument to strncpy() is almost always
> wrong and provides no extra benefit over strcpy(), and since 'ondemand'
> fits within 15 bytes" and it null terminates the string its safe to use
> strcpy().
>
> Fixes: 7fe2f6399a84 ("cpupowerutils - cpufrequtils extended with quite some features")
> Signed-off-by: Anders Roxell <[email protected]>
> ---
> tools/power/cpupower/bench/parse.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/power/cpupower/bench/parse.c b/tools/power/cpupower/bench/parse.c
> index 9ba8a44ad2a7..91b5b768ffd2 100644
> --- a/tools/power/cpupower/bench/parse.c
> +++ b/tools/power/cpupower/bench/parse.c
> @@ -145,7 +145,7 @@ struct config *prepare_default_config()
> config->cpu = 0;
> config->prio = SCHED_HIGH;
> config->verbose = 0;
> - strncpy(config->governor, "ondemand", 8);
> + strcpy(config->governor, "ondemand");
This change is fine, however continuing to use strncpy with sizeof(config->governor).

thanks,
-- Shuah

2018-08-28 09:32:52

by Anders Roxell

Subject: [PATCH v2] cpupower: remove stringop-truncation waring

The strncpy doesn't null terminate the string because the size is too
short by one byte.

parse.c: In function ‘prepare_default_config’:
parse.c:148:2: warning: ‘strncpy’ output truncated before terminating
nul copying 8 bytes from a string of the same length
[-Wstringop-truncation]
strncpy(config->governor, "ondemand", 8);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The normal method of passing the length of the destination buffer works
correctly here.

Fixes: 7fe2f6399a84 ("cpupowerutils - cpufrequtils extended with quite some features")
Signed-off-by: Anders Roxell <[email protected]>
---
tools/power/cpupower/bench/parse.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/power/cpupower/bench/parse.c b/tools/power/cpupower/bench/parse.c
index 9ba8a44ad2a7..84caee38418f 100644
--- a/tools/power/cpupower/bench/parse.c
+++ b/tools/power/cpupower/bench/parse.c
@@ -145,7 +145,7 @@ struct config *prepare_default_config()
config->cpu = 0;
config->prio = SCHED_HIGH;
config->verbose = 0;
- strncpy(config->governor, "ondemand", 8);
+ strncpy(config->governor, "ondemand", sizeof(config->governor));

config->output = stdout;

--
2.18.0

2018-08-28 21:50:15

by Shuah Khan

Subject: Re: [PATCH v2] cpupower: remove stringop-truncation waring

On 08/28/2018 03:31 AM, Anders Roxell wrote:
> The strncpy doesn't null terminate the string because the size is too
> short by one byte.
>
> parse.c: In function ‘prepare_default_config’:
> parse.c:148:2: warning: ‘strncpy’ output truncated before terminating
> nul copying 8 bytes from a string of the same length
> [-Wstringop-truncation]
> strncpy(config->governor, "ondemand", 8);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> The normal method of passing the length of the destination buffer works
> correctly here.
>
> Fixes: 7fe2f6399a84 ("cpupowerutils - cpufrequtils extended with quite some features")
> Signed-off-by: Anders Roxell <[email protected]>
> ---
> tools/power/cpupower/bench/parse.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/power/cpupower/bench/parse.c b/tools/power/cpupower/bench/parse.c
> index 9ba8a44ad2a7..84caee38418f 100644
> --- a/tools/power/cpupower/bench/parse.c
> +++ b/tools/power/cpupower/bench/parse.c
> @@ -145,7 +145,7 @@ struct config *prepare_default_config()
> config->cpu = 0;
> config->prio = SCHED_HIGH;
> config->verbose = 0;
> - strncpy(config->governor, "ondemand", 8);
> + strncpy(config->governor, "ondemand", sizeof(config->governor));
>
> config->output = stdout;
>
>

Thanks. Applied to cpupower git for 4.19-rc3

thanks,
-- Shuah