From nobody Wed Dec 17 20:59:18 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D110280038; Fri, 3 May 2024 22:50:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714776634; cv=none; b=cdnCQ5d0ZEL5cgXr/yDcEXbAUaBSS7ZZSZW+H2sFaj6iAw0tppbRc6bIxOydX/kla5egz4zSeuZAQX2MvLJDy8Vg3lizQusR0WDUx8cg+EMv41u7kcNDIWV7u4405ka5S/yfbZ+U2v5EH8HCUOHhu4c5foO0pcBgv1PsXUI5Z/E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714776634; c=relaxed/simple; bh=J3vNSDJFeIfDScHNg/+KPqU3RuxXUEMvLmcG3GsFWx4=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=CQDfMuxwjaBu9YBY7krnKhu+ZJiToO9sE1t6bkCcI2fPEYdWLjoAVrCWHSsAz6lwWD9QXxgLgrmRHGXOANqEs6etxKcyocHqgpvFZjjb415u95PMpgTklxIu5YMLN9CvEnUsGIDPEJHGyQ7MeyFhmQqUQU25Wq69o4U5q4dgNOY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id BB553C4AF1A; Fri, 3 May 2024 22:50:34 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1s31je-00000000NLb-0vti; Fri, 03 May 2024 18:50:34 -0400 Message-ID: <20240503225034.079856045@goodmis.org> User-Agent: quilt/0.68 Date: Fri, 03 May 2024 18:50:17 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org Subject: [for-linus][PATCH 4/9] eventfs: Free all of the eventfs_inode after RCU References: <20240503225013.519028385@goodmis.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Steven Rostedt (Google)" The freeing of eventfs_inode via a kfree_rcu() callback. But the content of the eventfs_inode was being freed after the last kref. This is dangerous, as changes are being made that can access the content of an eventfs_inode from an RCU loop. Instead of using kfree_rcu() use call_rcu() that calls a function to do all the freeing of the eventfs_inode after a RCU grace period has expired. Link: https://lore.kernel.org/linux-trace-kernel/20240502200905.370261163@g= oodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Fixes: 43aa6f97c2d03 ("eventfs: Get rid of dentry pointers without refcount= s") Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/event_inode.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index f5510e26f0f6..cc8b838bbe62 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -73,6 +73,21 @@ enum { =20 #define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1) =20 +static void free_ei_rcu(struct rcu_head *rcu) +{ + struct eventfs_inode *ei =3D container_of(rcu, struct eventfs_inode, rcu); + struct eventfs_root_inode *rei; + + kfree(ei->entry_attrs); + kfree_const(ei->name); + if (ei->is_events) { + rei =3D get_root_inode(ei); + kfree(rei); + } else { + kfree(ei); + } +} + /* * eventfs_inode reference count management. * @@ -85,7 +100,6 @@ static void release_ei(struct kref *ref) { struct eventfs_inode *ei =3D container_of(ref, struct eventfs_inode, kref= ); const struct eventfs_entry *entry; - struct eventfs_root_inode *rei; =20 WARN_ON_ONCE(!ei->is_freed); =20 @@ -95,14 +109,7 @@ static void release_ei(struct kref *ref) entry->release(entry->name, ei->data); } =20 - kfree(ei->entry_attrs); - kfree_const(ei->name); - if (ei->is_events) { - rei =3D get_root_inode(ei); - kfree_rcu(rei, ei.rcu); - } else { - kfree_rcu(ei, rcu); - } + call_rcu(&ei->rcu, free_ei_rcu); } =20 static inline void put_ei(struct eventfs_inode *ei) --=20 2.43.0