From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Date: Fri, 20 Jan 2012 22:34:04 +0000 (-0800)
Subject: kprobes: initialize before using a hlist
X-Git-Tag: v3.2.2~7
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=6ee7663e972835367a550bd6b9fecc1a9dc14ce1

kprobes: initialize before using a hlist

commit d496aab567e7e52b3e974c9192a5de6e77dce32c upstream.

Commit ef53d9c5e ("kprobes: improve kretprobe scalability with hashed
locking") 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>
Acked-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Srinivasa D S <srinivasa@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index e5d84644823b..52fd0499573f 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1077,6 +1077,7 @@ void __kprobes kprobe_flush_task(struct task_struct *tk)
 		/* 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 task_struct *tk)
 			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);