From: Richard Yao <ryao@cs.stonybrook.edu>
Date: Thu, 19 Jul 2012 22:37:56 +0000 (-0400)
Subject: Fix NULL pointer dereference on PaX/GRSecurity patched Linux 3.3 and later kernels
X-Git-Url: https://git.camperquake.de/gitweb.cgi?a=commitdiff_plain;h=ed3fc80048f1d11f0b77382f5c378bb4c11787fd;p=zfs.git

Fix NULL pointer dereference on PaX/GRSecurity patched Linux 3.3 and later kernels

Support for PaX/GRSecurity patched kernels was developed against Linux
3.2.  Unfortunately, an autotools check introduced for a Linux 3.3 API
fails on PaX/GRSecurity patched kernels. This causes the module to be
built against the Linux 3.2 ABI, which results in a NULL pointer
dereference at runtime.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Closes #794
Closes #809
---

diff --git a/config/kernel-show-options.m4 b/config/kernel-show-options.m4
index 1bddb0a..67d683c 100644
--- a/config/kernel-show-options.m4
+++ b/config/kernel-show-options.m4
@@ -6,11 +6,12 @@ AC_DEFUN([ZFS_AC_KERNEL_SHOW_OPTIONS], [
 
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
-		int (*show_options) (struct seq_file *, struct dentry *) = NULL;
-		struct super_operations sops __attribute__ ((unused));
 
-		sops.show_options = show_options;
+		int show_options (struct seq_file * x, struct dentry * y) { return 0; };
+		static struct super_operations sops __attribute__ ((unused)) = {
+			.show_options = show_options,
+		};
+	],[
 	],[
 		AC_MSG_RESULT([yes])
 		AC_DEFINE(HAVE_SHOW_OPTIONS_WITH_DENTRY, 1,
diff --git a/configure b/configure
index 245113e..4c1c210 100755
--- a/configure
+++ b/configure
@@ -15280,14 +15280,15 @@ cat >>conftest.$ac_ext <<_ACEOF
 
 		#include <linux/fs.h>
 
+		int show_options (struct seq_file * x, struct dentry * y) { return 0; };
+		static struct super_operations sops __attribute__ ((unused)) = {
+			.show_options = show_options,
+		};
+
 int
 main (void)
 {
 
-		int (*show_options) (struct seq_file *, struct dentry *) = NULL;
-		struct super_operations sops __attribute__ ((unused));
-
-		sops.show_options = show_options;
 
   ;
   return 0;
@@ -21807,14 +21808,15 @@ cat >>conftest.$ac_ext <<_ACEOF
 
 		#include <linux/fs.h>
 
+		int show_options (struct seq_file * x, struct dentry * y) { return 0; };
+		static struct super_operations sops __attribute__ ((unused)) = {
+			.show_options = show_options,
+		};
+
 int
 main (void)
 {
 
-		int (*show_options) (struct seq_file *, struct dentry *) = NULL;
-		struct super_operations sops __attribute__ ((unused));
-
-		sops.show_options = show_options;
 
   ;
   return 0;