[LTP] [PATCH v2 4/4] syscalls/statfs: Accept segfault instead of EFAULT

[Tudor Cretu]

The [f]statfs02 testsuites check that [f]statfs returns EFUALT when the
provided buf parameter is invalid. There are cases in which the supported
libcs don't exhibit this behaviour.

glibc versions newer than 2.34 and on systems that support [f]statfs64,
call the syscall with a local struct statfs and then copy the result
into buf. This throws a segfault for an invalid buf. musl dereferences buf
before the syscall is called and, similarly, throws a segfault.

Implement a sighandler to handle the cases where a segfault is thrown
instead of returning EFAULT.

Signed-off-by: Tudor Cretu <tudor.cretu@arm.com>
---
 testcases/kernel/syscalls/fstatfs/fstatfs02.c | 60 ++++++++++++++-----
 testcases/kernel/syscalls/statfs/statfs02.c   | 32 +++++++++-
 2 files changed, 73 insertions(+), 19 deletions(-)

diff --git a/testcases/kernel/syscalls/fstatfs/fstatfs02.c b/testcases/kernel/syscalls/fstatfs/fstatfs02.c
index db2230f82..e46b9df23 100644
--- a/testcases/kernel/syscalls/fstatfs/fstatfs02.c
+++ b/testcases/kernel/syscalls/fstatfs/fstatfs02.c
@@ -21,6 +21,8 @@
  *	Testcase to check fstatfs() sets errno correctly.
  */
 
+#include <setjmp.h>
+#include <signal.h>
 #include <sys/vfs.h>
 #include <sys/types.h>
 #include <sys/statfs.h>
@@ -28,9 +30,6 @@
 #include "test.h"
 #include "safe_macros.h"
 
-static void setup(void);
-static void cleanup(void);
-
 char *TCID = "fstatfs02";
 
 static struct statfs buf;
@@ -53,6 +52,13 @@ static struct test_case_t {
 
 int TST_TOTAL = ARRAY_SIZE(TC);
 
+static int sig_caught;
+static sigjmp_buf env;
+
+static void setup(void);
+static void cleanup(void);
+static void fstatfs_verify(const struct test_case_t *);
+
 int main(int ac, char **av)
 {
 	int lc;
@@ -67,23 +73,20 @@ int main(int ac, char **av)
 		tst_count = 0;
 
 		for (i = 0; i < TST_TOTAL; i++) {
+			sig_caught = 0;
+			if (sigsetjmp(env, 1) == 0)
+				fstatfs_verify(&TC[i]);
 
-			TEST(fstatfs(TC[i].fd, TC[i].sbuf));
+			if (!sig_caught)
+				continue;
 
-			if (TEST_RETURN != -1) {
-				tst_resm(TFAIL, "call succeeded unexpectedly");
+			if (TC[i].error == EFAULT && sig_caught == SIGSEGV) {
+				tst_resm(TINFO, "received SIGSEGV instead of returning EFAULT");
+				tst_resm(TPASS | TTERRNO, "expected failure");
 				continue;
 			}
 
-			if (TEST_ERRNO == TC[i].error) {
-				tst_resm(TPASS, "expected failure - "
-					 "errno = %d : %s", TEST_ERRNO,
-					 strerror(TEST_ERRNO));
-			} else {
-				tst_resm(TFAIL, "unexpected error - %d : %s - "
-					 "expected %d", TEST_ERRNO,
-					 strerror(TEST_ERRNO), TC[i].error);
-			}
+			tst_resm(TFAIL, "Received an unexpected signal: %d", sig_caught);
 		}
 	}
 	cleanup();
@@ -91,9 +94,16 @@ int main(int ac, char **av)
 	tst_exit();
 }
 
+static void sighandler(int sig)
+{
+	sig_caught = sig;
+	siglongjmp(env, 1);
+
+}
+
 static void setup(void)
 {
-	tst_sig(NOFORK, DEF_HANDLER, cleanup);
+	tst_sig(NOFORK, sighandler, cleanup);
 
 	TEST_PAUSE;
 
@@ -103,6 +113,24 @@ static void setup(void)
 #endif
 }
 
+static void fstatfs_verify(const struct test_case_t *test)
+{
+	TEST(fstatfs(test->fd, test->sbuf));
+
+	if (TEST_RETURN != -1) {
+		tst_resm(TFAIL, "call succeeded unexpectedly");
+		return;
+	}
+
+	if (TEST_ERRNO == test->error) {
+		tst_resm(TPASS, "expected failure - errno = %d : %s",
+			 TEST_ERRNO, strerror(TEST_ERRNO));
+	} else {
+		tst_resm(TFAIL, "unexpected error - %d : %s - expected %d",
+			 TEST_ERRNO, strerror(TEST_ERRNO), test->error);
+	}
+}
+
 static void cleanup(void)
 {
 #ifndef UCLINUX
diff --git a/testcases/kernel/syscalls/statfs/statfs02.c b/testcases/kernel/syscalls/statfs/statfs02.c
index 279665f86..7f150d1d9 100644
--- a/testcases/kernel/syscalls/statfs/statfs02.c
+++ b/testcases/kernel/syscalls/statfs/statfs02.c
@@ -32,6 +32,8 @@
  *		ELOOP.
  */
 
+#include <setjmp.h>
+#include <signal.h>
 #include <sys/types.h>
 #include <sys/statfs.h>
 #include <sys/stat.h>
@@ -70,6 +72,10 @@ static struct test_case_t {
 };
 
 int TST_TOTAL = ARRAY_SIZE(TC);
+
+static int sig_caught;
+static sigjmp_buf env;
+
 static void setup(void);
 static void cleanup(void);
 static void statfs_verify(const struct test_case_t *);
@@ -85,17 +91,37 @@ int main(int ac, char **av)
 
 	for (lc = 0; TEST_LOOPING(lc); lc++) {
 		tst_count = 0;
-		for (i = 0; i < TST_TOTAL; i++)
-			statfs_verify(&TC[i]);
+		for (i = 0; i < TST_TOTAL; i++) {
+			sig_caught = 0;
+			if (sigsetjmp(env, 1) == 0)
+				statfs_verify(&TC[i]);
+
+			if (!sig_caught)
+				continue;
+
+			if (TC[i].exp_error == EFAULT && sig_caught == SIGSEGV) {
+				tst_resm(TINFO, "received SIGSEGV instead of returning EFAULT");
+				tst_resm(TPASS | TTERRNO, "expected failure");
+				continue;
+			}
+
+			tst_resm(TFAIL, "Received an unexpected signal: %d", sig_caught);
+		}
 	}
 
 	cleanup();
 	tst_exit();
 }
 
+static void sighandler(int sig)
+{
+	sig_caught = sig;
+	siglongjmp(env, 1);
+}
+
 static void setup(void)
 {
-	tst_sig(NOFORK, DEF_HANDLER, cleanup);
+	tst_sig(NOFORK, sighandler, cleanup);
 
 	TEST_PAUSE;
 
-- 
2.25.1