[Bug libc/3332] New: dl_execstack PaX support

["robert at linuxfromscratch dot org" <sourceware-bugzilla at sourceware dot org>]

The following patch is needed for PaX (pax.grsecurity.net) Linux kernel 
support. I don't think the changes will affect non-PaX systems:

diff -Naur glibc-2.3.6.orig/sysdeps/unix/sysv/linux/dl-execstack.c
glibc-2.3.6/sysdeps/unix/sysv/linux/dl-execstack.c
--- glibc-2.3.6.orig/sysdeps/unix/sysv/linux/dl-execstack.c	2005-07-18 
04:11:19.000000000 +0000
+++ glibc-2.3.6/sysdeps/unix/sysv/linux/dl-execstack.c	2005-11-13 
08:50:35.000000000 +0000
@@ -58,14 +58,20 @@
 					__stack_prot) == 0, 1))
 	goto return_success;
 # if __ASSUME_PROT_GROWSUPDOWN == 0
-      if (errno == EINVAL)
+      if (errno == EINVAL) {
 	no_growsupdown = true;
-      else
+      } else {
 # endif
+      if (errno == EACCES)		/* PAX is enabled */
+	return 0;
+      else
 	{
 	  result = errno;
 	  goto out;
 	}
+# if __ASSUME_PROT_GROWSUPDOWN == 0
+      }
+# endif
     }
 #endif
 
@@ -89,11 +95,14 @@
 	page -= size;
       else
 	{
-	  if (errno != ENOMEM)	/* Unexpected failure mode.  */
+	  if (errno == EACCES) {	/* PAX is enabled  */
+	    return 0;
+	  } else if (errno != ENOMEM) { /* Unexpected failure mode.  */
 	    {
 	      result = errno;
 	      goto out;
 	    }
+	  }
 
 	  if (size == GLRO(dl_pagesize))
 	    /* We just tried to mprotect the top hole page and failed.
@@ -115,11 +124,14 @@
 	page += size;
       else
 	{
-	  if (errno != ENOMEM)	/* Unexpected failure mode.  */
+	  if (errno == EACCES) {	/* PAX is enabled */
+	    return 0;
+	  } else if (errno != ENOMEM)  /* Unexpected failure mode.  */
 	    {
 	      result = errno;
 	      goto out;
 	    }
+	  }
 
 	  if (size == GLRO(dl_pagesize))
 	    /* We just tried to mprotect the lowest hole page and failed.

-- 
           Summary: dl_execstack PaX support
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: robert at linuxfromscratch dot org
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=3332

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