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 4C0108F57 for ; Sun, 16 Jul 2023 20:46:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C16A2C433C8; Sun, 16 Jul 2023 20:46:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689540400; bh=U7ZsPrUblNl0UJ+Qxq3gGSSoqYDcKQ1i1Y7w+DrSTMQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V3hYsZsLsWapnDE2WeQqsjjOJ4phCQbAJjLRaCV0NBMrq+GQYGLQclxRosLdcPNtQ Suug529+slKie+PAtyf+wFUF0E2z0F1Vkmkpma5ojdGlOeDTAqwQRpue8ip+VzFmhS FmnBgtgOpCRxxtq1FZGlUyTbQq9p9OPF4D6Ea7AM= 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 6.1 350/591] dax: Fix dax_mapping_release() use after free Date: Sun, 16 Jul 2023 21:48:09 +0200 Message-ID: <20230716194932.966169208@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230716194923.861634455@linuxfoundation.org> References: <20230716194923.861634455@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 c64e7076537cb..d7a838f651813 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -621,10 +621,12 @@ 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) @@ -764,6 +766,7 @@ 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