[PATCH] kprobes: initialize before using a hlist

[PATCH] kprobes: initialize before using a hlist

[Ananth N Mavinakayanahalli]

From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>

Commit ef53d9c5e introduced a bug where we can potentially leak
kretprobe_instances since we initialize a hlist head after having
used it.

Initialize the hlist head before using it.

Reported by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
CC: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
CC: <stable@kernel.org>
---
 kernel/kprobes.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-3.2/kernel/kprobes.c
===================================================================
--- linux-3.2.orig/kernel/kprobes.c
+++ linux-3.2/kernel/kprobes.c
@@ -1077,6 +1077,7 @@ void __kprobes kprobe_flush_task(struct 
 		/* Early boot.  kretprobe_table_locks not yet initialized. */
 		return;
 
+	INIT_HLIST_HEAD(&empty_rp);
 	hash = hash_ptr(tk, KPROBE_HASH_BITS);
 	head = &kretprobe_inst_table[hash];
 	kretprobe_table_lock(hash, &flags);
@@ -1085,7 +1086,6 @@ void __kprobes kprobe_flush_task(struct 
 			recycle_rp_inst(ri, &empty_rp);
 	}
 	kretprobe_table_unlock(hash, &flags);
-	INIT_HLIST_HEAD(&empty_rp);
 	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 		hlist_del(&ri->hlist);
 		kfree(ri);