kernel/linux.git/drivers/md/dm-thin.c, branch v6.1.168

dm thin: make get_first_thin use rcu-safe list first function

2025-01-17T12:34:41+00:00

commit 80f130bfad1dab93b95683fc39b87235682b8f72 upstream. The documentation in rculist.h explains the absence of list_empty_rcu() and cautions programmers against relying on a list_empty() -> list_first() sequence in RCU safe code. This is because each of these functions performs its own READ_ONCE() of the list head. This can lead to a situation where the list_empty() sees a valid list entry, but the subsequent list_first() sees a different view of list head state after a modification. In the case of dm-thin, this author had a production box crash from a GP fault in the process_deferred_bios path. This function saw a valid list head in get_first_thin() but when it subsequently dereferenced that and turned it into a thin_c, it got the inside of the struct pool, since the list was now empty and referring to itself. The kernel on which this occurred printed both a warning about a refcount_t being saturated, and a UBSAN error for an out-of-bounds cpuid access in the queued spinlock, prior to the fault itself. When the resulting kdump was examined, it was possible to see another thread patiently waiting in thin_dtr's synchronize_rcu. The thin_dtr call managed to pull the thin_c out of the active thins list (and have it be the last entry in the active_thins list) at just the wrong moment which lead to this crash. Fortunately, the fix here is straight forward. Switch get_first_thin() function to use list_first_or_null_rcu() which performs just a single READ_ONCE() and returns NULL if the list is already empty. This was run against the devicemapper test suite's thin-provisioning suites for delete and suspend and no regressions were observed. Signed-off-by: Krister Johansen Fixes: b10ebd34ccca ("dm thin: fix rcu_read_lock being held in code that can sleep") Cc: stable@vger.kernel.org Acked-by: Ming-Hung Tsai Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman

dm thin: Add missing destroy_work_on_stack()

2024-12-14T18:54:16+00:00

commit e74fa2447bf9ed03d085b6d91f0256cc1b53f1a8 upstream. This commit add missed destroy_work_on_stack() operations for pw->worker in pool_work_wait(). Fixes: e7a3e871d895 ("dm thin: cleanup noflush_work to use a proper completion") Cc: stable@vger.kernel.org Signed-off-by: Yuan Can Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman

dm: address indent/space issues

2024-03-26T22:21:02+00:00

[ Upstream commit 255e2646496fcbf836a3dfe1b535692f09f11b45 ] Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer Stable-dep-of: b4d78cfeb304 ("dm-integrity: align the outgoing bio in integrity_recheck") Signed-off-by: Sasha Levin

dm thin: fix issue_discard to pass GFP_NOIO to __blkdev_issue_discard

2023-06-21T14:00:55+00:00

commit 722d90822321497e2837cfc9000202e256e6b32f upstream. issue_discard() passes GFP_NOWAIT to __blkdev_issue_discard() despite its code assuming bio_alloc() always succeeds. Commit 3dba53a958a75 ("dm thin: use __blkdev_issue_discard for async discard support") clearly shows where things went bad: Before commit 3dba53a958a75, dm-thin.c's open-coded __blkdev_issue_discard_async() properly handled using GFP_NOWAIT. Unfortunately __blkdev_issue_discard() doesn't and it was missed during review. Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm: change "unsigned" to "unsigned int"

2023-04-13T14:55:17+00:00

[ Upstream commit 86a3238c7b9b759cb864f4f768ab2e24687dc0e6 ] Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer Stable-dep-of: f7b58a69fad9 ("dm: fix improper splitting for abnormal bios") Signed-off-by: Sasha Levin

dm thin: fix deadlock when swapping to thin device

2023-03-30T10:49:23+00:00

commit 9bbf5feecc7eab2c370496c1c161bbfe62084028 upstream. This is an already known issue that dm-thin volume cannot be used as swap, otherwise a deadlock may happen when dm-thin internal memory demand triggers swap I/O on the dm-thin volume itself. But thanks to commit a666e5c05e7c ("dm: fix deadlock when swapping to encrypted device"), the limit_swap_bios target flag can also be used for dm-thin to avoid the recursive I/O when it is used as swap. Fix is to simply set ti->limit_swap_bios to true in both pool_ctr() and thin_ctr(). In my test, I create a dm-thin volume /dev/vg/swap and use it as swap device. Then I run fio on another dm-thin volume /dev/vg/main and use large --blocksize to trigger swap I/O onto /dev/vg/swap. The following fio command line is used in my test, fio --name recursive-swap-io --lockmem 1 --iodepth 128 \ --ioengine libaio --filename /dev/vg/main --rw randrw \ --blocksize 1M --numjobs 32 --time_based --runtime=12h Without this fix, the whole system can be locked up within 15 seconds. With this fix, there is no any deadlock or hung task observed after 2 hours of running fio. Furthermore, if blocksize is changed from 1M to 128M, after around 30 seconds fio has no visible I/O, and the out-of-memory killer message shows up in kernel message. After around 20 minutes all fio processes are killed and the whole system is back to being alive. This is exactly what is expected when recursive I/O happens on dm-thin volume when it is used as swap. Depends-on: a666e5c05e7c ("dm: fix deadlock when swapping to encrypted device") Cc: stable@vger.kernel.org Signed-off-by: Coly Li Acked-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm thin: add cond_resched() to various workqueue loops

2023-03-10T08:34:01+00:00

[ Upstream commit e4f80303c2353952e6e980b23914e4214487f2a6 ] Otherwise on resource constrained systems these workqueues may be too greedy. Signed-off-by: Mike Snitzer Signed-off-by: Sasha Levin

dm thin: Fix UAF in run_timer_softirq()

2023-01-07T10:11:45+00:00

commit 88430ebcbc0ec637b710b947738839848c20feff upstream. When dm_resume() and dm_destroy() are concurrent, it will lead to UAF, as follows: BUG: KASAN: use-after-free in __run_timers+0x173/0x710 Write of size 8 at addr ffff88816d9490f0 by task swapper/0/0 Call Trace: dump_stack_lvl+0x73/0x9f print_report.cold+0x132/0xaa2 _raw_spin_lock_irqsave+0xcd/0x160 __run_timers+0x173/0x710 kasan_report+0xad/0x110 __run_timers+0x173/0x710 __asan_store8+0x9c/0x140 __run_timers+0x173/0x710 call_timer_fn+0x310/0x310 pvclock_clocksource_read+0xfa/0x250 kvm_clock_read+0x2c/0x70 kvm_clock_get_cycles+0xd/0x20 ktime_get+0x5c/0x110 lapic_next_event+0x38/0x50 clockevents_program_event+0xf1/0x1e0 run_timer_softirq+0x49/0x90 __do_softirq+0x16e/0x62c __irq_exit_rcu+0x1fa/0x270 irq_exit_rcu+0x12/0x20 sysvec_apic_timer_interrupt+0x8e/0xc0 One of the concurrency UAF can be shown as below: use free do_resume | __find_device_hash_cell | dm_get | atomic_inc(&md->holders) | | dm_destroy | __dm_destroy | if (!dm_suspended_md(md)) | atomic_read(&md->holders) | msleep(1) dm_resume | __dm_resume | dm_table_resume_targets | pool_resume | do_waker #add delay work | dm_put | atomic_dec(&md->holders) | | dm_table_destroy | pool_dtr | __pool_dec | __pool_destroy | destroy_workqueue | kfree(pool) # free pool time out __do_softirq run_timer_softirq # pool has already been freed This can be easily reproduced using: 1. create thin-pool 2. dmsetup suspend pool 3. dmsetup resume pool 4. dmsetup remove_all # Concurrent with 3 The root cause of this UAF bug is that dm_resume() adds timer after dm_destroy() skips cancelling the timer because of suspend status. After timeout, it will call run_timer_softirq(), however pool has already been freed. The concurrency UAF bug will happen. Therefore, cancelling timer again in __pool_destroy(). Cc: stable@vger.kernel.org Fixes: 991d9fa02da0d ("dm: add thin provisioning target") Signed-off-by: Luo Meng Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm thin: resume even if in FAIL mode

2023-01-07T10:11:45+00:00

commit 19eb1650afeb1aa86151f61900e9e5f1de5d8d02 upstream. If a thinpool set fail_io while suspending, resume will fail with: device-mapper: resume ioctl on vg-thinpool failed: Invalid argument The thin-pool also can't be removed if an in-flight bio is in the deferred list. This can be easily reproduced using: echo "offline" > /sys/block/sda/device/state dd if=/dev/zero of=/dev/mapper/thin bs=4K count=1 dmsetup suspend /dev/mapper/pool mkfs.ext4 /dev/mapper/thin dmsetup resume /dev/mapper/pool The root cause is maybe_resize_data_dev() will check fail_io and return error before called dm_resume. Fix this by adding FAIL mode check at the end of pool_preresume(). Cc: stable@vger.kernel.org Fixes: da105ed5fd7e ("dm thin metadata: introduce dm_pool_abort_metadata") Signed-off-by: Luo Meng Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm thin: fix use-after-free crash in dm_sm_register_threshold_callback

2022-07-15T22:09:14+00:00

Fault inject on pool metadata device reports: BUG: KASAN: use-after-free in dm_pool_register_metadata_threshold+0x40/0x80 Read of size 8 at addr ffff8881b9d50068 by task dmsetup/950 CPU: 7 PID: 950 Comm: dmsetup Tainted: G W 5.19.0-rc6 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 Call Trace: dump_stack_lvl+0x34/0x44 print_address_description.constprop.0.cold+0xeb/0x3f4 kasan_report.cold+0xe6/0x147 dm_pool_register_metadata_threshold+0x40/0x80 pool_ctr+0xa0a/0x1150 dm_table_add_target+0x2c8/0x640 table_load+0x1fd/0x430 ctl_ioctl+0x2c4/0x5a0 dm_ctl_ioctl+0xa/0x10 __x64_sys_ioctl+0xb3/0xd0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 This can be easily reproduced using: echo offline > /sys/block/sda/device/state dd if=/dev/zero of=/dev/mapper/thin bs=4k count=10 dmsetup load pool --table "0 20971520 thin-pool /dev/sda /dev/sdb 128 0 0" If a metadata commit fails, the transaction will be aborted and the metadata space maps will be destroyed. If a DM table reload then happens for this failed thin-pool, a use-after-free will occur in dm_sm_register_threshold_callback (called from dm_pool_register_metadata_threshold). Fix this by in dm_pool_register_metadata_threshold() by returning the -EINVAL error if the thin-pool is in fail mode. Also fail pool_ctr() with a new error message: "Error registering metadata threshold". Fixes: ac8c3f3df65e4 ("dm thin: generate event when metadata threshold passed") Cc: stable@vger.kernel.org Reported-by: Hulk Robot Signed-off-by: Luo Meng Signed-off-by: Mike Snitzer