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Subject[PATCH] [10/11] SYSCTL: Use RCU protected sysctl for ocfs group add helper
Date

This avoids races with unlocked sysctl()

Cc: joel.becker@oracle.com
Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
fs/ocfs2/stackglue.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
Index: linux-2.6.33-rc1-ak/fs/ocfs2/stackglue.c
===================================================================
--- linux-2.6.33-rc1-ak.orig/fs/ocfs2/stackglue.c
+++ linux-2.6.33-rc1-ak/fs/ocfs2/stackglue.c
@@ -27,6 +27,7 @@
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <linux/sysctl.h>
+#include <linux/rcustring.h>

#include "ocfs2_fs.h"

@@ -40,7 +41,7 @@ static struct ocfs2_locking_protocol *lp
static DEFINE_SPINLOCK(ocfs2_stack_lock);
static LIST_HEAD(ocfs2_stack_list);
static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
-static char ocfs2_hb_ctl_path[OCFS2_MAX_HB_CTL_PATH] = "/sbin/ocfs2_hb_ctl";
+static char *ocfs2_hb_ctl_path = "/sbin/ocfs2_hb_ctl";

/*
* The stack currently in use. If not null, active_stack->sp_count > 0,
@@ -395,8 +396,15 @@ static void ocfs2_leave_group(const char
{
int ret;
char *argv[5], *envp[3];
+ char *helper;

- argv[0] = ocfs2_hb_ctl_path;
+ helper = access_rcu_string(ocfs2_hb_ctl_path, OCFS2_MAX_HB_CTL_PATH, GFP_KERNEL);
+ if (!helper) {
+ printk(KERN_ERR "ocfs2_leave_group: no memory\n");
+ return;
+ }
+
+ argv[0] = helper;
argv[1] = "-K";
argv[2] = "-u";
argv[3] = (char *)group;
@@ -414,6 +422,7 @@ static void ocfs2_leave_group(const char
"\"%s %s %s %s\"\n",
ret, argv[0], argv[1], argv[2], argv[3]);
}
+ kfree(helper);
}

/*
@@ -621,10 +630,10 @@ error:
static ctl_table ocfs2_nm_table[] = {
{
.procname = "hb_ctl_path",
- .data = ocfs2_hb_ctl_path,
+ .data = &ocfs2_hb_ctl_path,
.maxlen = OCFS2_MAX_HB_CTL_PATH,
.mode = 0644,
- .proc_handler = proc_dostring,
+ .proc_handler = proc_rcu_string,
},
{ }
};

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