From be48c412f6ebf38849213c19547bc6d5b692b5e5 Mon Sep 17 00:00:00 2001 From: Kairui Song Date: Tue, 10 Dec 2024 00:57:15 +0800 Subject: zram: refuse to use zero sized block device as backing device Patch series "zram: fix backing device setup issue", v2. This series fixes two bugs of backing device setting: - ZRAM should reject using a zero sized (or the uninitialized ZRAM device itself) as the backing device. - Fix backing device leaking when removing a uninitialized ZRAM device. This patch (of 2): Setting a zero sized block device as backing device is pointless, and one can easily create a recursive loop by setting the uninitialized ZRAM device itself as its own backing device by (zram0 is uninitialized): echo /dev/zram0 > /sys/block/zram0/backing_dev It's definitely a wrong config, and the module will pin itself, kernel should refuse doing so in the first place. By refusing to use zero sized device we avoided misuse cases including this one above. Link: https://lkml.kernel.org/r/20241209165717.94215-1-ryncsn@gmail.com Link: https://lkml.kernel.org/r/20241209165717.94215-2-ryncsn@gmail.com Fixes: 013bf95a83ec ("zram: add interface to specif backing device") Signed-off-by: Kairui Song Reported-by: Desheng Wu Reviewed-by: Sergey Senozhatsky Cc: Signed-off-by: Andrew Morton --- drivers/block/zram/zram_drv.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'drivers/block') diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 3dee026988dc..e86cc3d2f4d2 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -614,6 +614,12 @@ static ssize_t backing_dev_store(struct device *dev, } nr_pages = i_size_read(inode) >> PAGE_SHIFT; + /* Refuse to use zero sized device (also prevents self reference) */ + if (!nr_pages) { + err = -EINVAL; + goto out; + } + bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long); bitmap = kvzalloc(bitmap_sz, GFP_KERNEL); if (!bitmap) { -- cgit v1.2.3 From 74363ec674cb172d8856de25776c8f3103f05e2f Mon Sep 17 00:00:00 2001 From: Kairui Song Date: Tue, 10 Dec 2024 00:57:16 +0800 Subject: zram: fix uninitialized ZRAM not releasing backing device Setting backing device is done before ZRAM initialization. If we set the backing device, then remove the ZRAM module without initializing the device, the backing device reference will be leaked and the device will be hold forever. Fix this by always reset the ZRAM fully on rmmod or reset store. Link: https://lkml.kernel.org/r/20241209165717.94215-3-ryncsn@gmail.com Fixes: 013bf95a83ec ("zram: add interface to specif backing device") Signed-off-by: Kairui Song Reported-by: Desheng Wu Suggested-by: Sergey Senozhatsky Reviewed-by: Sergey Senozhatsky Cc: Signed-off-by: Andrew Morton --- drivers/block/zram/zram_drv.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'drivers/block') diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index e86cc3d2f4d2..45df5eeabc5e 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1444,12 +1444,16 @@ static void zram_meta_free(struct zram *zram, u64 disksize) size_t num_pages = disksize >> PAGE_SHIFT; size_t index; + if (!zram->table) + return; + /* Free all pages that are still in this zram device */ for (index = 0; index < num_pages; index++) zram_free_page(zram, index); zs_destroy_pool(zram->mem_pool); vfree(zram->table); + zram->table = NULL; } static bool zram_meta_alloc(struct zram *zram, u64 disksize) @@ -2326,11 +2330,6 @@ static void zram_reset_device(struct zram *zram) zram->limit_pages = 0; - if (!init_done(zram)) { - up_write(&zram->init_lock); - return; - } - set_capacity_and_notify(zram->disk, 0); part_stat_set_all(zram->disk->part0, 0); -- cgit v1.2.3 From 75cd4005da5492129917a4a4ee45e81660556104 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Wed, 25 Dec 2024 19:06:40 +0800 Subject: ublk: detach gendisk from ublk device if add_disk() fails Inside ublk_abort_requests(), gendisk is grabbed for aborting all inflight requests. And ublk_abort_requests() is called when exiting the uring context or handling timeout. If add_disk() fails, the gendisk may have been freed when calling ublk_abort_requests(), so use-after-free can be caused when getting disk's reference in ublk_abort_requests(). Fixes the bug by detaching gendisk from ublk device if add_disk() fails. Fixes: bd23f6c2c2d0 ("ublk: quiesce request queue when aborting queue") Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20241225110640.351531-1-ming.lei@redhat.com Signed-off-by: Jens Axboe --- drivers/block/ublk_drv.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) (limited to 'drivers/block') diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index d4aed12dd436..934ab9332c80 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1618,6 +1618,21 @@ static void ublk_unquiesce_dev(struct ublk_device *ub) blk_mq_kick_requeue_list(ub->ub_disk->queue); } +static struct gendisk *ublk_detach_disk(struct ublk_device *ub) +{ + struct gendisk *disk; + + /* Sync with ublk_abort_queue() by holding the lock */ + spin_lock(&ub->lock); + disk = ub->ub_disk; + ub->dev_info.state = UBLK_S_DEV_DEAD; + ub->dev_info.ublksrv_pid = -1; + ub->ub_disk = NULL; + spin_unlock(&ub->lock); + + return disk; +} + static void ublk_stop_dev(struct ublk_device *ub) { struct gendisk *disk; @@ -1631,14 +1646,7 @@ static void ublk_stop_dev(struct ublk_device *ub) ublk_unquiesce_dev(ub); } del_gendisk(ub->ub_disk); - - /* Sync with ublk_abort_queue() by holding the lock */ - spin_lock(&ub->lock); - disk = ub->ub_disk; - ub->dev_info.state = UBLK_S_DEV_DEAD; - ub->dev_info.ublksrv_pid = -1; - ub->ub_disk = NULL; - spin_unlock(&ub->lock); + disk = ublk_detach_disk(ub); put_disk(disk); unlock: mutex_unlock(&ub->mutex); @@ -2336,7 +2344,7 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd) out_put_cdev: if (ret) { - ub->dev_info.state = UBLK_S_DEV_DEAD; + ublk_detach_disk(ub); ublk_put_device(ub); } if (ret) -- cgit v1.2.3