runtime: don't assume AT_RANDOM provide 4-byte aligned ptr

R=dave, remyoudompheng
CC=golang-dev
https://golang.org/cl/6854056

diff --git a/src/pkg/runtime/signal_linux_arm.c b/src/pkg/runtime/signal_linux_arm.c
index e12c54d97275eb939ce6fb4e653734d191fd1801..48336c0aff9a15225ee230807af31af6f53fa15d 100644 (file)
--- a/src/pkg/runtime/signal_linux_arm.c
+++ b/src/pkg/runtime/signal_linux_arm.c
@@ -173,11 +173,14 @@ runtime·checkgoarm(void)
 void
 runtime·setup_auxv(int32 argc, void *argv_list)
 {
-       byte **argv = &argv_list;
+       byte **argv;
        byte **envp;
+       byte *rnd;
        uint32 *auxv;
        uint32 t;
 
+       argv = &argv_list;
+
        // skip envp to get to ELF auxiliary vector.
        for(envp = &argv[argc+1]; *envp != nil; envp++)
                ;
@@ -186,8 +189,10 @@ runtime·setup_auxv(int32 argc, void *argv_list)
        for(auxv=(uint32*)envp; auxv[0] != AT_NULL; auxv += 2) {
                switch(auxv[0]) {
                case AT_RANDOM: // kernel provided 16-byte worth of random data
-                       if(auxv[1])
-                               runtime·randomNumber = *(uint32*)(auxv[1] + 4);
+                       if(auxv[1]) {
+                               rnd = (byte*)auxv[1];
+                               runtime·randomNumber = rnd[4] | rnd[5]<<8 | rnd[6]<<16 | rnd[7]<<24;
+                       }
                        break;
                case AT_PLATFORM: // v5l, v6l, v7l
                        if(auxv[1]) {