[patch] patch to reenable ASLR after setup

sbcl-reenable-asrl.patch (text/plain), 1.95 KB, created by Andreas Wiese on 2015-08-28 13:41:31 UTC

commit a5b12abcf4e291de70397254e042619e19f73a98
Author: Andreas Wiese <[e-mail]>
Date:   Thu Aug 27 16:54:14 2015 +0200

    runtime/linux-os: Reenable ASLR after restart for forked children.
    
    If we detect that sbcl has been restarted due to enabled ASLR, call
    personality() again to restore the default for forked children.  Leaving
    it disabled imposes a security risk.

diff --git a/src/runtime/linux-os.c b/src/runtime/linux-os.c
index 33a3683..95e8cfa 100644
--- a/src/runtime/linux-os.c
+++ b/src/runtime/linux-os.c
@@ -64,6 +64,7 @@
 /* Prototype for personality(2). Done inline here since the header file
  * for this isn't available on old versions of glibc. */
 int personality (unsigned long);
+#define ADDR_NO_RANDOMIZE 0x0040000
 #else
 #include <sys/personality.h>
 #endif
@@ -261,9 +262,8 @@ os_init(char *argv[], char *envp[])
         || major_version >= 3)
     {
         int pers = personality(0xffffffffUL);
-        /* 0x40000 aka. ADDR_NO_RANDOMIZE */
-        if (!(pers & 0x40000)) {
-            int retval = personality(pers | 0x40000);
+        if (!(pers & ADDR_NO_RANDOMIZE)) {
+            int retval = personality(pers | ADDR_NO_RANDOMIZE);
             /* Allegedly some Linux kernels (the reported case was
              * "hardened Linux 2.6.7") won't set the new personality,
              * but nor will they return -1 for an error. So as a
@@ -298,7 +298,12 @@ os_init(char *argv[], char *envp[])
             fprintf(stderr, "WARNING:\
 \nCouldn't re-execute SBCL with proper personality flags (/proc isn't mounted? setuid?)\
 \nTrying to continue anyway.\n");
-        } else {
+        } else if (getenv("SBCL_IS_RESTARTING")) {
+            /* We restarted due to previously enabled ASLR.  Now,
+             * reenable it for fork()'ed children. */
+            int pers = personality(0xffffffffUL);
+            personality(pers & ~ADDR_NO_RANDOMIZE);
+
             unsetenv("SBCL_IS_RESTARTING");
         }
     }