[123/129] kprobes: initialize before using a hlist

[Greg KH]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------
Content-Length: 1477
Lines: 43

From: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>

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@xxxxxxxxxx>
Acked-by: Jim Keniston <jkenisto@xxxxxxxxxx>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Srinivasa D S <srinivasa@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 kernel/kprobes.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/kprobes.c
+++ b/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);


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