basic: getauxval(AT_RANDOM) is apparently not necessarily aligned

Let's make sure we read it in a way compatible with non-aligned memory.

Fixes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=812928

1 files changed, 8 insertions, 7 deletions

diff --git a/src/basic/random-util.c b/src/basic/random-util.c
index 2f5c16e2a..34cc7cbce 100644
--- a/src/basic/random-util.c
+++ b/src/basic/random-util.c
@@ -94,17 +94,18 @@ void initialize_srand(void) {
         if (srand_called)
                 return;
 
-        x = 0;
-
 #ifdef HAVE_SYS_AUXV_H
-        /* The kernel provides us with a bit of entropy in auxv, so
-         * let's try to make use of that to seed the pseudo-random
-         * generator. It's better than nothing... */
+        /* The kernel provides us with 16 bytes of entropy in auxv, so let's try to make use of that to seed the
+         * pseudo-random generator. It's better than nothing... */
 
         auxv = (void*) getauxval(AT_RANDOM);
-        if (auxv)
-                x ^= *(unsigned*) auxv;
+        if (auxv) {
+                assert_cc(sizeof(x) < 16);
+                memcpy(&x, auxv, sizeof(x));
+        } else
 #endif
+                x = 0;
+
 
         x ^= (unsigned) now(CLOCK_REALTIME);
         x ^= (unsigned) gettid();