Re: selftests/powerpc: Use snprintf to construct DSCR sysfs interface paths

[Michael Ellerman]

On Thu, 2017-09-28 at 13:34:26 UTC, Seth Forshee wrote:
> Currently sprintf is used, and while paths should never exceed
> the size of the buffer it is theoretically possible since
> dirent.d_name is 256 bytes. As a result this trips
> -Wformat-overflow, and since the test is built with -Wall -Werror
> the causes the build to fail. Switch to using snprintf and skip
> any paths which are too long for the filename buffer.
> 
> Signed-off-by: Seth Forshee 

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/06755a871314c7443a89c09650cdb3

cheers

[PATCH] selftests/powerpc: Use snprintf to construct DSCR sysfs interface paths

[Seth Forshee]

Currently sprintf is used, and while paths should never exceed
the size of the buffer it is theoretically possible since
dirent.d_name is 256 bytes. As a result this trips
-Wformat-overflow, and since the test is built with -Wall -Werror
the causes the build to fail. Switch to using snprintf and skip
any paths which are too long for the filename buffer.

Signed-off-by: Seth Forshee 
---
 tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c | 6 +-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c 
b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
index 17fb1b43c320..1899bd85121f 100644
--- a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
+++ b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
@@ -53,6 +53,8 @@ static int check_all_cpu_dscr_defaults(unsigned long val)
}
 
while ((dp = readdir(sysfs))) {
+   int len;
+
if (!(dp->d_type & DT_DIR))
continue;
if (!strcmp(dp->d_name, "cpuidle"))
@@ -60,7 +62,9 @@ static int check_all_cpu_dscr_defaults(unsigned long val)
if (!strstr(dp->d_name, "cpu"))
continue;
 
-   sprintf(file, "%s%s/dscr", CPU_PATH, dp->d_name);
+   len = snprintf(file, LEN_MAX, "%s%s/dscr", CPU_PATH, 
dp->d_name);
+   if (len >= LEN_MAX)
+   continue;
if (access(file, F_OK))
continue;
 
-- 
2.14.1