kprobes: initialize before using a hlist

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 95dd7212e610..29f5b65bee29 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);