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Wed, 9 Mar 2022 17:26:31 +0800 Received: from localhost.localdomain (10.175.127.227) by dggpeml500006.china.huawei.com (7.185.36.76) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Wed, 9 Mar 2022 17:26:31 +0800 From: Luo Meng To: , , Date: Wed, 9 Mar 2022 17:41:48 +0800 Message-ID: <20220309094148.2164043-1-luomeng12@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpeml500006.china.huawei.com (7.185.36.76) X-CFilter-Loop: Reflected X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Subject: [dm-devel] [PTACH] dm-mpath: fix UAF in multipath_message() X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: luomeng12@huawei.com, yukuai3@huawei.com Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com If dm_get_device() create dd in multipath_message(), and then call table_deps() after dm_put_table_device(), it will lead to concurrency UAF bugs. One of the concurrency UAF can be shown as below: (USE) | (FREE) | target_message | multipath_message | dm_put_device | dm_put_table_device # | kfree(td) # table_device *td ioctl # DM_TABLE_DEPS_CMD | ... table_deps | ... dm_get_live_or_inactive_table | ... retrieve_dep | ... list_for_each_entry | ... deps->dev[count++] = | ... huge_encode_dev | ... (dd->dm_dev->bdev->bd_dev) | list_del(&dd->list) | kfree(dd) # dm_dev_internal The root cause of UAF bugs is that find_device() failed in dm_get_device() and will create dd and refcount set 1, kfree() in dm_put_table() is not protected. When td, which there are still pointers point to, is released, the concurrency UAF bug will happen. This patch add a flag to determine whether to create a new dd. Signed-off-by: Luo Meng --- drivers/md/dm-mpath.c | 2 +- drivers/md/dm-table.c | 43 +++++++++++++++++++++-------------- include/linux/device-mapper.h | 2 ++ 3 files changed, 29 insertions(+), 18 deletions(-) diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index f4719b65e5e3..1f8b29ed7979 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -1999,7 +1999,7 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv, goto out; } - r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev); + r = __dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev, false); if (r) { DMWARN("message: error getting device %s", argv[1]); diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index e43096cfe9e2..b8fc7e0afb84 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -340,12 +340,8 @@ dev_t dm_get_dev_t(const char *path) } EXPORT_SYMBOL_GPL(dm_get_dev_t); -/* - * Add a device to the list, or just increment the usage count if - * it's already present. - */ -int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, - struct dm_dev **result) +int __dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, + struct dm_dev **result, bool create_dd) { int r; dev_t dev; @@ -369,19 +365,21 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, dd = find_device(&t->devices, dev); if (!dd) { - dd = kmalloc(sizeof(*dd), GFP_KERNEL); - if (!dd) - return -ENOMEM; - - if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) { - kfree(dd); - return r; - } + if (create_dd) { + dd = kmalloc(sizeof(*dd), GFP_KERNEL); + if (!dd) + return -ENOMEM; - refcount_set(&dd->count, 1); - list_add(&dd->list, &t->devices); - goto out; + if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) { + kfree(dd); + return r; + } + refcount_set(&dd->count, 1); + list_add(&dd->list, &t->devices); + goto out; + } else + return -ENODEV; } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) { r = upgrade_mode(dd, mode, t->md); if (r) @@ -392,6 +390,17 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, *result = dd->dm_dev; return 0; } +EXPORT_SYMBOL(__dm_get_device); + +/* + * Add a device to the list, or just increment the usage count if + * it's already present. + */ +int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, + struct dm_dev **result) +{ + return __dm_get_device(ti, path, mode, result, true); +} EXPORT_SYMBOL(dm_get_device); static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index b26fecf6c8e8..a1b44789e3dc 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -168,6 +168,8 @@ dev_t dm_get_dev_t(const char *path); int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, struct dm_dev **result); void dm_put_device(struct dm_target *ti, struct dm_dev *d); +int __dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, + struct dm_dev **result, bool create_dd); /* * Information about a target type