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 9D07C1E48A; Mon, 18 Aug 2025 13:48:45 +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=1755524925; cv=none; b=Lb5ScQDurLcpqsFmHMQmbZ7XTwIhjYOGqf8lo2LzD9ulpezkpAO4Y756bkjx8+7kUEV0J+6UAgTilC1Xw04Sejptbnm+44YQa5gRBh8qvv4H2CtA+Qg4Z/FUvF4v4BbuUZYGCQswApnM18ms9WifEpH99Fry9+6IVcaM16BMgMY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755524925; c=relaxed/simple; bh=6eLygwi+eSDNGepirZf7ynWnXNCj770u6caBHR6o5rQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DV2hZAUPRn2cRG6wMuSXYunA0VgIGJj6Kg7/FVjWHsqp+pCHu3CMvQ8DHeF/+CMlZomEECwa8/FyMOjaIvz4MLm4lRU5Ij7nqYagDGpdQk4l2Zeevpj8yv6T+6en7ZHru4vrwXS6mic+7cJjC1CjT66kKvtABryc+BKNythHyFA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sgxr2XI3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sgxr2XI3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0CD66C4CEEB; Mon, 18 Aug 2025 13:48:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755524925; bh=6eLygwi+eSDNGepirZf7ynWnXNCj770u6caBHR6o5rQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sgxr2XI3HwX45W8a4hgqOvUZkrOkN0dqHjbooqS0bEyhBHgb0tGa56IGcXDM1LXGb aqIwZGGKZVurau0JhcoMQwMU97+Eg3fF8pPxh4Mn6Q85Of20W/8IKyvb5FVLAFyYg/ BRr0HQEYy1/g1/RwmDOrvU16N1ZCEMxcZSbfelQM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yu Kuai , Xiao Ni , Sasha Levin Subject: [PATCH 6.16 106/570] md: call del_gendisk in control path Date: Mon, 18 Aug 2025 14:41:33 +0200 Message-ID: <20250818124509.890618243@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250818124505.781598737@linuxfoundation.org> References: <20250818124505.781598737@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiao Ni [ Upstream commit 9e59d609763f70a992a8f3808dabcce60f14eb5c ] Now del_gendisk and put_disk are called asynchronously in workqueue work. The asynchronous way has a problem that the device node can still exist after mdadm --stop command returns in a short window. So udev rule can open this device node and create the struct mddev in kernel again. So put del_gendisk in control path and still leave put_disk in md_kobj_release to avoid uaf of gendisk. Function del_gendisk can't be called with reconfig_mutex. If it's called with reconfig mutex, a deadlock can happen. del_gendisk waits all sysfs files access to finish and sysfs file access waits reconfig mutex. So put del_gendisk after releasing reconfig mutex. But there is still a window that sysfs can be accessed between mddev_unlock and del_gendisk. So some actions (add disk, change level, .e.g) can happen which lead unexpected results. MD_DELETED is used to resolve this problem. MD_DELETED is set before releasing reconfig mutex and it should be checked for these sysfs access which need reconfig mutex. For sysfs access which don't need reconfig mutex, del_gendisk will wait them to finish. But it doesn't need to do this in function mddev_lock_nointr. There are ten places that call it. * Five of them are in dm raid which we don't need to care. MD_DELETED is only used for md raid. * stop_sync_thread, md_do_sync and md_start_sync are related sync request, and it needs to wait sync thread to finish before stopping an array. * md_ioctl: md_open is called before md_ioctl, so ->openers is added. It will fail to stop the array. So it doesn't need to check MD_DELETED here * md_set_readonly: It needs to call mddev_set_closing_and_sync_blockdev when setting readonly or read_auto. So it will fail to stop the array too because MD_CLOSING is already set. Reviewed-by: Yu Kuai Signed-off-by: Xiao Ni Link: https://lore.kernel.org/linux-raid/20250611073108.25463-2-xni@redhat.com Signed-off-by: Yu Kuai Signed-off-by: Sasha Levin --- drivers/md/md.c | 33 +++++++++++++++++++++++---------- drivers/md/md.h | 26 ++++++++++++++++++++++++-- 2 files changed, 47 insertions(+), 12 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 10670c62b09e..c16c7feb6034 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -636,9 +636,6 @@ static void __mddev_put(struct mddev *mddev) mddev->ctime || mddev->hold_active) return; - /* Array is not configured at all, and not held active, so destroy it */ - set_bit(MD_DELETED, &mddev->flags); - /* * Call queue_work inside the spinlock so that flush_workqueue() after * mddev_find will succeed in waiting for the work to be done. @@ -873,6 +870,16 @@ void mddev_unlock(struct mddev *mddev) kobject_del(&rdev->kobj); export_rdev(rdev, mddev); } + + /* Call del_gendisk after release reconfig_mutex to avoid + * deadlock (e.g. call del_gendisk under the lock and an + * access to sysfs files waits the lock) + * And MD_DELETED is only used for md raid which is set in + * do_md_stop. dm raid only uses md_stop to stop. So dm raid + * doesn't need to check MD_DELETED when getting reconfig lock + */ + if (test_bit(MD_DELETED, &mddev->flags)) + del_gendisk(mddev->gendisk); } EXPORT_SYMBOL_GPL(mddev_unlock); @@ -5774,19 +5781,30 @@ md_attr_store(struct kobject *kobj, struct attribute *attr, struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr); struct mddev *mddev = container_of(kobj, struct mddev, kobj); ssize_t rv; + struct kernfs_node *kn = NULL; if (!entry->store) return -EIO; if (!capable(CAP_SYS_ADMIN)) return -EACCES; + + if (entry->store == array_state_store && cmd_match(page, "clear")) + kn = sysfs_break_active_protection(kobj, attr); + spin_lock(&all_mddevs_lock); if (!mddev_get(mddev)) { spin_unlock(&all_mddevs_lock); + if (kn) + sysfs_unbreak_active_protection(kn); return -EBUSY; } spin_unlock(&all_mddevs_lock); rv = entry->store(mddev, page, length); mddev_put(mddev); + + if (kn) + sysfs_unbreak_active_protection(kn); + return rv; } @@ -5794,12 +5812,6 @@ static void md_kobj_release(struct kobject *ko) { struct mddev *mddev = container_of(ko, struct mddev, kobj); - if (mddev->sysfs_state) - sysfs_put(mddev->sysfs_state); - if (mddev->sysfs_level) - sysfs_put(mddev->sysfs_level); - - del_gendisk(mddev->gendisk); put_disk(mddev->gendisk); } @@ -6646,8 +6658,9 @@ static int do_md_stop(struct mddev *mddev, int mode) mddev->bitmap_info.offset = 0; export_array(mddev); - md_clean(mddev); + set_bit(MD_DELETED, &mddev->flags); + if (mddev->hold_active == UNTIL_STOP) mddev->hold_active = 0; } diff --git a/drivers/md/md.h b/drivers/md/md.h index d45a9e6ead80..67b365621507 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -700,11 +700,26 @@ static inline bool reshape_interrupted(struct mddev *mddev) static inline int __must_check mddev_lock(struct mddev *mddev) { - return mutex_lock_interruptible(&mddev->reconfig_mutex); + int ret; + + ret = mutex_lock_interruptible(&mddev->reconfig_mutex); + + /* MD_DELETED is set in do_md_stop with reconfig_mutex. + * So check it here. + */ + if (!ret && test_bit(MD_DELETED, &mddev->flags)) { + ret = -ENODEV; + mutex_unlock(&mddev->reconfig_mutex); + } + + return ret; } /* Sometimes we need to take the lock in a situation where * failure due to interrupts is not acceptable. + * It doesn't need to check MD_DELETED here, the owner which + * holds the lock here can't be stopped. And all paths can't + * call this function after do_md_stop. */ static inline void mddev_lock_nointr(struct mddev *mddev) { @@ -713,7 +728,14 @@ static inline void mddev_lock_nointr(struct mddev *mddev) static inline int mddev_trylock(struct mddev *mddev) { - return mutex_trylock(&mddev->reconfig_mutex); + int ret; + + ret = mutex_trylock(&mddev->reconfig_mutex); + if (!ret && test_bit(MD_DELETED, &mddev->flags)) { + ret = -ENODEV; + mutex_unlock(&mddev->reconfig_mutex); + } + return ret; } extern void mddev_unlock(struct mddev *mddev); -- 2.39.5