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selftests/x86: Clean up and document sscanf() usage 

Replace a couple of magically connected buffer length literal constants with
a common definition that makes their relationship obvious. Also document
why our sscanf() usage is safe.

No intended functional changes.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Andrew Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kselftest@vger.kernel.org
Cc: shuah@kernel.org
Link: http://lkml.kernel.org/r/20180211205924.GA23210@light.dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Dominik Brodowski 2018-02-11 21:59:24 +01:00 committed by Ingo Molnar
parent 198ee8e175
commit d8e92de8ef
2 changed files with 16 additions and 6 deletions
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11
tools/testing/selftests/x86/test_vdso.c
View File

@ -26,6 +26,9 @@
# endif
#endif
/* max length of lines in /proc/self/maps - anything longer is skipped here */
#define MAPS_LINE_LEN 128
int nerrs = 0;
typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
@ -37,17 +40,19 @@ static void *vsyscall_getcpu(void)
{
#ifdef __x86_64__
FILE *maps;
char line[128];
char line[MAPS_LINE_LEN];
bool found = false;
maps = fopen("/proc/self/maps", "r");
if (!maps) /* might still be present, but ignore it here, as we test vDSO not vsyscall */
return NULL;
while (fgets(line, sizeof(line), maps)) {
while (fgets(line, MAPS_LINE_LEN, maps)) {
char r, x;
void *start, *end;
char name[128];
char name[MAPS_LINE_LEN];
/* sscanf() is safe here as strlen(name) >= strlen(line) */
if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
&start, &end, &r, &x, name) != 5)
continue;

11
tools/testing/selftests/x86/test_vsyscall.c
View File

@ -33,6 +33,9 @@
# endif
#endif
/* max length of lines in /proc/self/maps - anything longer is skipped here */
#define MAPS_LINE_LEN 128
static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
int flags)
{
@ -98,7 +101,7 @@ static int init_vsys(void)
#ifdef __x86_64__
int nerrs = 0;
FILE *maps;
char line[128];
char line[MAPS_LINE_LEN];
bool found = false;
maps = fopen("/proc/self/maps", "r");
@ -108,10 +111,12 @@ static int init_vsys(void)
return 0;
}
while (fgets(line, sizeof(line), maps)) {
while (fgets(line, MAPS_LINE_LEN, maps)) {
char r, x;
void *start, *end;
char name[128];
char name[MAPS_LINE_LEN];
/* sscanf() is safe here as strlen(name) >= strlen(line) */
if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
&start, &end, &r, &x, name) != 5)
continue;