linux-kernel - [PATCH tip/core/rcu 5/7] rcu: Add support for debug_objects debugging for kfree

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20191210041147.3181-5-paulmck@kernel.org>
Date:   Mon,  9 Dec 2019 20:11:45 -0800
From:   paulmck@...nel.org
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com, mingo@...nel.org,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH tip/core/rcu 5/7] rcu: Add support for debug_objects debugging for kfree_rcu()

From: "Joel Fernandes (Google)" <joel@...lfernandes.org>

This commit applies RCU's debug_objects debugging to the new batched
kfree_rcu() implementations.  The object is queued at the kfree_rcu()
call and dequeued during reclaim.

Tested that enabling CONFIG_DEBUG_OBJECTS_RCU_HEAD successfully detects
double kfree_rcu() calls.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
[ paulmck: Fix IRQ per kbuild test robot <lkp@...el.com> feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/tree.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a40fd58..0512221 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2749,6 +2749,7 @@ static void kfree_rcu_work(struct work_struct *work)
 	for (; head; head = next) {
 		next = head->next;
 		// Potentially optimize with kfree_bulk in future.
+		debug_rcu_head_unqueue(head);
 		__rcu_reclaim(rcu_state.name, head);
 		cond_resched_tasks_rcu_qs();
 	}
@@ -2855,6 +2856,12 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
 		spin_lock(&krcp->lock);
 
 	// Queue the object but don't yet schedule the batch.
+	if (debug_rcu_head_queue(head)) {
+		// Probable double kfree_rcu(), just leak.
+		WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
+			  __func__, head);
+		goto unlock_return;
+	}
 	head->func = func;
 	head->next = krcp->head;
 	krcp->head = head;
@@ -2866,6 +2873,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
 		schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
 	}
 
+unlock_return:
 	if (krcp->initialized)
 		spin_unlock(&krcp->lock);
 	local_irq_restore(flags);
-- 
2.9.5