[PATCH v2] Linux: Fix UTC offset setting in settimeofday for __TIMESIZE != 64

[Florian Weimer]

The time argument is NULL in this case, and attempt to convert it
leads to a null pointer dereference.

This fixes commit d2e3b697da2433c08702f95c76458c51545c3df1
("y2038: linux: Provide __settimeofday64 implementation").

---
v2: Add just a null pointer check.  Tested on x86_64-linux-gnu and
    i686-linux-gnu.

 sysdeps/unix/sysv/linux/settimeofday.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/settimeofday.c b/sysdeps/unix/sysv/linux/settimeofday.c
index ea45f1d7cb..6f4bc7ef3c 100644
--- a/sysdeps/unix/sysv/linux/settimeofday.c
+++ b/sysdeps/unix/sysv/linux/settimeofday.c
@@ -25,6 +25,7 @@
 int
 __settimeofday64 (const struct __timeval64 *tv, const struct timezone *tz)
 {
+  /* Backwards compatibility for setting the UTC offset.  */
   if (__glibc_unlikely (tz != 0))
     {
       if (tv != 0)
@@ -45,9 +46,13 @@ libc_hidden_def (__settimeofday64)
 int
 __settimeofday (const struct timeval *tv, const struct timezone *tz)
 {
-  struct __timeval64 tv64 = valid_timeval_to_timeval64 (*tv);
-
-  return __settimeofday64 (&tv64, tz);
+  if (__glibc_unlikely (tv == NULL))
+      return __settimeofday64 (NULL, tz);
+  else
+    {
+      struct __timeval64 tv64 = valid_timeval_to_timeval64 (*tv);
+      return __settimeofday64 (&tv64, tz);
+    }
 }
 #endif
 weak_alias (__settimeofday, settimeofday);