2019-01-31 19:51:19

by Shuah Khan

Subject: [PATCH] selftests: ir: fix warning: ‘%s’ directive output may be truncated

Fix the following warning by sizing the buffer to max. of sysfs
path max. size + d_name max. size.

gcc -Wall -O2 -I../../../include/uapi ir_loopback.c -o ../tools/testing/selftests/ir/ir_loopback
ir_loopback.c: In function ‘lirc_open’:
ir_loopback.c:71:37: warning: ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size 95 [-Wformat-truncation=]
snprintf(buf, sizeof(buf), "/dev/%s", dent->d_name);
^~
In file included from /usr/include/stdio.h:862:0,
from ir_loopback.c:14:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:64:10: note: ‘__builtin___snprintf_chk’ output between 6 and 261 bytes into a destination of size 100
return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
__bos (__s), __fmt, __va_arg_pack ());
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan <[email protected]>
---
tools/testing/selftests/ir/ir_loopback.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/ir/ir_loopback.c b/tools/testing/selftests/ir/ir_loopback.c
index 858c19caf224..8cdf1b89ac9c 100644
--- a/tools/testing/selftests/ir/ir_loopback.c
+++ b/tools/testing/selftests/ir/ir_loopback.c
@@ -27,6 +27,8 @@

#define TEST_SCANCODES 10
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+#define SYSFS_PATH_MAX 256
+#define DNAME_PATH_MAX 256

static const struct {
enum rc_proto proto;
@@ -56,7 +58,7 @@ static const struct {
int lirc_open(const char *rc)
{
struct dirent *dent;
- char buf[100];
+ char buf[SYSFS_PATH_MAX + DNAME_PATH_MAX];
DIR *d;
int fd;

--
2.17.1

2019-02-04 21:50:25

by Sean Young

Subject: Re: [PATCH] selftests: ir: fix w arning: ‘%s’ directive output may be truncated

On Thu, Jan 31, 2019 at 12:43:12PM -0700, Shuah Khan wrote:
> Fix the following warning by sizing the buffer to max. of sysfs
> path max. size + d_name max. size.
>
> gcc -Wall -O2 -I../../../include/uapi ir_loopback.c -o ../tools/testing/selftests/ir/ir_loopback
> ir_loopback.c: In function ‘lirc_open’:
> ir_loopback.c:71:37: warning: ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size 95 [-Wformat-truncation=]
> snprintf(buf, sizeof(buf), "/dev/%s", dent->d_name);
> ^~
> In file included from /usr/include/stdio.h:862:0,
> from ir_loopback.c:14:
> /usr/include/x86_64-linux-gnu/bits/stdio2.h:64:10: note: ‘__builtin___snprintf_chk’ output between 6 and 261 bytes into a destination of size 100
> return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> __bos (__s), __fmt, __va_arg_pack ());
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Signed-off-by: Shuah Khan <[email protected]>

Thank you for catching and fixing these. For all three patches:

Acked-by: Sean Young <[email protected]>

> ---
> tools/testing/selftests/ir/ir_loopback.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/ir/ir_loopback.c b/tools/testing/selftests/ir/ir_loopback.c
> index 858c19caf224..8cdf1b89ac9c 100644
> --- a/tools/testing/selftests/ir/ir_loopback.c
> +++ b/tools/testing/selftests/ir/ir_loopback.c
> @@ -27,6 +27,8 @@
>
> #define TEST_SCANCODES 10
> #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
> +#define SYSFS_PATH_MAX 256
> +#define DNAME_PATH_MAX 256
>
> static const struct {
> enum rc_proto proto;
> @@ -56,7 +58,7 @@ static const struct {
> int lirc_open(const char *rc)
> {
> struct dirent *dent;
> - char buf[100];
> + char buf[SYSFS_PATH_MAX + DNAME_PATH_MAX];
> DIR *d;
> int fd;
>
> --
> 2.17.1