[LTP] [PATCH 4/4] syscalls/statfs: Avoid dereferencing invalid buf in libc

[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.

To avoid dereferencing an invalid buf in libc, bypass the [f]statfs wrapper
and call the syscall directly. Consistently with the libc wrappers,
choose [f]statfs64 instead of [f]statfs if the target supports it.

Signed-off-by: Tudor Cretu <tudor.cretu@arm.com>
---
 testcases/kernel/syscalls/fstatfs/fstatfs02.c | 7 ++++++-
 testcases/kernel/syscalls/statfs/statfs02.c   | 7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/testcases/kernel/syscalls/fstatfs/fstatfs02.c b/testcases/kernel/syscalls/fstatfs/fstatfs02.c
index db2230f82..c1af07070 100644
--- a/testcases/kernel/syscalls/fstatfs/fstatfs02.c
+++ b/testcases/kernel/syscalls/fstatfs/fstatfs02.c
@@ -25,6 +25,7 @@
 #include <sys/types.h>
 #include <sys/statfs.h>
 #include <errno.h>
+#include "lapi/syscalls.h"
 #include "test.h"
 #include "safe_macros.h"
 
@@ -68,7 +69,11 @@ int main(int ac, char **av)
 
 		for (i = 0; i < TST_TOTAL; i++) {
 
-			TEST(fstatfs(TC[i].fd, TC[i].sbuf));
+#if __NR_fstatfs64 != __LTP__NR_INVALID_SYSCALL
+			TEST(tst_syscall(__NR_fstatfs64, TC[i].fd, TC[i].sbuf));
+#else
+			TEST(tst_syscall(__NR_fstatfs, TC[i].fd, TC[i].sbuf));
+#endif
 
 			if (TEST_RETURN != -1) {
 				tst_resm(TFAIL, "call succeeded unexpectedly");
diff --git a/testcases/kernel/syscalls/statfs/statfs02.c b/testcases/kernel/syscalls/statfs/statfs02.c
index 279665f86..e1afbda39 100644
--- a/testcases/kernel/syscalls/statfs/statfs02.c
+++ b/testcases/kernel/syscalls/statfs/statfs02.c
@@ -39,6 +39,7 @@
 #include <sys/vfs.h>
 #include <sys/mman.h>
 #include <errno.h>
+#include "lapi/syscalls.h"
 #include "test.h"
 #include "safe_macros.h"
 
@@ -116,7 +117,11 @@ static void setup(void)
 
 static void statfs_verify(const struct test_case_t *test)
 {
-	TEST(statfs(test->path, test->buf));
+#if __NR_statfs64 != __LTP__NR_INVALID_SYSCALL
+	TEST(tst_syscall(__NR_statfs64, test->path, test->buf));
+#else
+	TEST(tst_syscall(__NR_statfs, test->path, test->buf));
+#endif
 
 	if (TEST_RETURN != -1) {
 		tst_resm(TFAIL, "call succeeded unexpectedly");
-- 
2.25.1