linux-kernel - [PATCH] bsdacct: delete timer with sync intension

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Message-Id: <201003251735.10907.vgusev@openvz.org>
Date:	Thu, 25 Mar 2010 17:35:10 +0300
From:	Vitaliy Gusev <vgusev@...nvz.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Pavel Emelyanov <xemul@...nvz.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] bsdacct: delete timer with sync intension

acct_exit_ns --> acct_file_reopen deletes timer without
check timer execution on other CPUs. So acct_timeout() can
change an unmapped memory.

Signed-off-by: Vitaliy Gusev <vgusev@...nvz.org>

---
 kernel/acct.c |   17 +++++++++--------
 1 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/kernel/acct.c b/kernel/acct.c
index a6605ca..6ac80ca 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -353,17 +353,18 @@ restart:
 
 void acct_exit_ns(struct pid_namespace *ns)
 {
-	struct bsd_acct_struct *acct;
+	struct bsd_acct_struct *acct = ns->bacct;
 
-	spin_lock(&acct_lock);
-	acct = ns->bacct;
-	if (acct != NULL) {
-		if (acct->file != NULL)
-			acct_file_reopen(acct, NULL, NULL);
+	if (acct == NULL)
+		return;
 
-		kfree(acct);
-	}
+	del_timer_sync(&acct->timer);
+	spin_lock(&acct_lock);
+	if (acct->file != NULL)
+		acct_file_reopen(acct, NULL, NULL);
 	spin_unlock(&acct_lock);
+
+	kfree(acct);
 }
 
 /*
--
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