[PATCH] Increase judgment on buf.

[Peng Fan <fanpeng@loongson.cn>]

When buf is empty, if it is not checked, the subsequent assignment
operation will trigger a page fault. This is unnecessary.

Signed-off-by: lixing <lixing@loongson.cn>
Signed-off-by: Peng Fan <fanpeng@loongson.cn>
---
 sysdeps/unix/sysv/linux/fstatat64.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/fstatat64.c b/sysdeps/unix/sysv/linux/fstatat64.c
index 3509d3ca6d..b635a8299a 100644
--- a/sysdeps/unix/sysv/linux/fstatat64.c
+++ b/sysdeps/unix/sysv/linux/fstatat64.c
@@ -52,9 +52,13 @@ fstatat64_time64_statx (int fd, const char *file, struct __stat64_t64 *buf,
 {
   /* 32-bit kABI with default 64-bit time_t, e.g. arc, riscv32.   Also
      64-bit time_t support is done through statx syscall.  */
-  struct statx tmp;
+  struct statx tmp, *ptr;
+  if (buf)
+	ptr = &tmp;
+  else
+	ptr = NULL;
   int r = INTERNAL_SYSCALL_CALL (statx, fd, file, AT_NO_AUTOMOUNT | flag,
-				 STATX_BASIC_STATS, &tmp);
+				 STATX_BASIC_STATS, ptr);
   if (r != 0)
     return r;
 
-- 
2.33.0