From mboxrd@z Thu Jan 1 00:00:00 1970 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 8ABE41ED38 for ; Tue, 25 Jul 2023 11:20:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AC59C433C8; Tue, 25 Jul 2023 11:20:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1690284027; bh=XybTZgvXNmP3FNR6Bi2LoI/BTu04xweEx+woRbdWRXc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FJOsNEh4kqGD3+XPTUjjhu0HjNCRwDtcvyNJbhX3cRAuYVZ9Y1y+wVGlgS8IokfXR jHxgj5UeeW2AHExq3sWVOpLQaBu5arGPQL2atOOnmd9HQF28aN9l6P8T3hAjOjKWV2 f+UldmjZUTsvM/6q4a3qkStrsmIs7aDR8T1Ni5eA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Dan Williams , Dave Jiang , Fan Ni , Ira Weiny , Vishal Verma , Sasha Levin Subject: [PATCH 5.10 208/509] dax: Fix dax_mapping_release() use after free Date: Tue, 25 Jul 2023 12:42:27 +0200 Message-ID: <20230725104603.257993864@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230725104553.588743331@linuxfoundation.org> References: <20230725104553.588743331@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Dan Williams [ Upstream commit 6d24b170a9db0456f577b1ab01226a2254c016a8 ] A CONFIG_DEBUG_KOBJECT_RELEASE test of removing a device-dax region provider (like modprobe -r dax_hmem) yields: kobject: 'mapping0' (ffff93eb460e8800): kobject_release, parent 0000000000000000 (delayed 2000) [..] DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 23 PID: 282 at kernel/locking/lockdep.c:232 __lock_acquire+0x9fc/0x2260 [..] RIP: 0010:__lock_acquire+0x9fc/0x2260 [..] Call Trace: [..] lock_acquire+0xd4/0x2c0 ? ida_free+0x62/0x130 _raw_spin_lock_irqsave+0x47/0x70 ? ida_free+0x62/0x130 ida_free+0x62/0x130 dax_mapping_release+0x1f/0x30 device_release+0x36/0x90 kobject_delayed_cleanup+0x46/0x150 Due to attempting ida_free() on an ida object that has already been freed. Devices typically only hold a reference on their parent while registered. If a child needs a parent object to complete its release it needs to hold a reference that it drops from its release callback. Arrange for a dax_mapping to pin its parent dev_dax instance until dax_mapping_release(). Fixes: 0b07ce872a9e ("device-dax: introduce 'mapping' devices") Signed-off-by: Dan Williams Link: https://lore.kernel.org/r/168577283412.1672036.16111545266174261446.stgit@dwillia2-xfh.jf.intel.com Reviewed-by: Dave Jiang Reviewed-by: Fan Ni Reviewed-by: Ira Weiny Signed-off-by: Vishal Verma Signed-off-by: Sasha Levin --- drivers/dax/bus.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index a02777c93c07b..48b7f0a64eb81 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -592,10 +592,12 @@ EXPORT_SYMBOL_GPL(alloc_dax_region); static void dax_mapping_release(struct device *dev) { struct dax_mapping *mapping = to_dax_mapping(dev); - struct dev_dax *dev_dax = to_dev_dax(dev->parent); + struct device *parent = dev->parent; + struct dev_dax *dev_dax = to_dev_dax(parent); ida_free(&dev_dax->ida, mapping->id); kfree(mapping); + put_device(parent); } static void unregister_dax_mapping(void *data) @@ -735,6 +737,7 @@ static int devm_register_dax_mapping(struct dev_dax *dev_dax, int range_id) dev = &mapping->dev; device_initialize(dev); dev->parent = &dev_dax->dev; + get_device(dev->parent); dev->type = &dax_mapping_type; dev_set_name(dev, "mapping%d", mapping->id); rc = device_add(dev); -- 2.39.2