Re: [PATCH][RESEND] kprobes: initialize before using a hlist

(2012/01/10 9:47), Jim Keniston wrote:

On Mon, 2012-01-09 at 13:50 +0530, Ananth N Mavinakayanahalli wrote:

quoted

From: Ananth N Mavinakayanahalli <redacted>

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.

(Resent with correct email ID for -stable)

Reported by: Jim Keniston [off-list ref]
Signed-off-by: Ananth N Mavinakayanahalli <redacted>
Cc: Masami Hiramatsu <redacted>
Cc: <redacted>

Acked-by: Jim Keniston <redacted>

Acked-by: Masami Hiramatsu <redacted>

Thank you!

quoted

---
 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);

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-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com