kernel/linux.git/drivers/block/rbd.c, branch v6.12.92

rbd: eliminate a race in lock_dwork draining on unmap

2026-06-01T15:46:20+00:00

commit 9fc75b71fdd38465c76c6f6a884cdd4ae3c72d90 upstream. Given how rbd_lock_add_request() and rbd_img_exclusive_lock() are written, lock_dwork may be (re)queued more than it's actually needed: for example in case a new I/O request comes in while we are in the middle of rbd_acquire_lock() on behalf of another I/O request. This is expected and with rbd_release_lock() preemptively canceling lock_dwork is benign under normal operation. A more problematic example is maybe_kick_acquire(): if (have_requests || delayed_work_pending(&rbd_dev->lock_dwork)) { dout("%s rbd_dev %p kicking lock_dwork\n", __func__, rbd_dev); mod_delayed_work(rbd_dev->task_wq, &rbd_dev->lock_dwork, 0); } It's not unrealistic for lock_dwork to get canceled right after delayed_work_pending() returns true and for mod_delayed_work() to requeue it right there anyway. This is a classic TOCTOU race. When it comes to unmapping the image, there is an implicit assumption of no self-initiated exclusive lock activity past the point of return from rbd_dev_image_unlock() which unlocks the lock if it happens to be held. This unlock is assumed to be final and lock_dwork (as well as all other exclusive lock tasks, really) isn't expected to get queued again. However, lock_dwork is canceled only in cancel_tasks_sync() (i.e. later in the unmap sequence) and on top of that the cancellation can get in effect nullified by maybe_kick_acquire(). This may result in rbd_acquire_lock() executing after rbd_dev_device_release() and rbd_dev_image_release() run and free and/or reset a bunch of things. One of the possible failure modes then is a violated rbd_assert(rbd_image_format_valid(rbd_dev->image_format)); in rbd_dev_header_info() which is called via rbd_dev_refresh() from rbd_post_acquire_action(). Redo exclusive lock task draining to provide saner semantics and try to meet the assumptions around rbd_dev_image_unlock(). Cc: stable@vger.kernel.org Signed-off-by: Ilya Dryomov Reviewed-by: Viacheslav Dubeyko Signed-off-by: Greg Kroah-Hartman

rbd: fix null-ptr-deref when device_add_disk() fails

2026-05-07T04:09:31+00:00

commit d1fef92e414433ca7b89abf85cb0df42b8d475eb upstream. do_rbd_add() publishes the device with device_add() before calling device_add_disk(). If device_add_disk() fails after device_add() succeeds, the error path calls rbd_free_disk() directly and then later falls through to rbd_dev_device_release(), which calls rbd_free_disk() again. This double teardown can leave blk-mq cleanup operating on invalid state and trigger a null-ptr-deref in __blk_mq_free_map_and_rqs(), reached from blk_mq_free_tag_set(). Fix this by following the normal remove ordering: call device_del() before rbd_dev_device_release() when device_add_disk() fails after device_add(). That keeps the teardown sequence consistent and avoids re-entering disk cleanup through the wrong path. The bug was first flagged by an experimental analysis tool we are developing for kernel memory-management bugs while analyzing v6.13-rc1. The tool is still under development and is not yet publicly available. We reproduced the bug on v7.0 with a real Ceph backend and a QEMU x86_64 guest booted with KASAN and CONFIG_FAILSLAB enabled. The reproducer confines failslab injections to the __add_disk() range and injects fail-nth while mapping an RBD image through /sys/bus/rbd/add_single_major. On the unpatched kernel, fail-nth=4 reliably triggered the fault: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 0 UID: 0 PID: 273 Comm: bash Not tainted 7.0.0-01247-gd60bc1401583 #6 PREEMPT(lazy) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 RIP: 0010:__blk_mq_free_map_and_rqs+0x8c/0x240 Code: 00 00 48 8b 6b 60 41 89 f4 49 c1 e4 03 4c 01 e5 45 85 ed 0f 85 0a 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 e9 48 c1 e9 03 <80> 3c 01 00 0f 85 31 01 00 00 4c 8b 6d 00 4d 85 ed 0f 84 e2 00 00 RSP: 0018:ff1100000ab0fac8 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ff1100000c4806a0 RCX: 0000000000000000 RDX: 0000000000000002 RSI: 0000000000000000 RDI: ff1100000c4806f4 RBP: 0000000000000000 R08: 0000000000000001 R09: ffe21c000189001b R10: ff1100000c4800df R11: ff1100006cf37be0 R12: 0000000000000000 R13: 0000000000000000 R14: ff1100000c480700 R15: ff1100000c480004 FS: 00007f0fbe8fe740(0000) GS:ff110000e5851000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe53473b2e0 CR3: 0000000012eef000 CR4: 00000000007516f0 PKRU: 55555554 Call Trace: blk_mq_free_tag_set+0x77/0x460 do_rbd_add+0x1446/0x2b80 ? __pfx_do_rbd_add+0x10/0x10 ? lock_acquire+0x18c/0x300 ? find_held_lock+0x2b/0x80 ? sysfs_file_kobj+0xb6/0x1b0 ? __pfx_sysfs_kf_write+0x10/0x10 kernfs_fop_write_iter+0x2f4/0x4a0 vfs_write+0x98e/0x1000 ? expand_files+0x51f/0x850 ? __pfx_vfs_write+0x10/0x10 ksys_write+0xf2/0x1d0 ? __pfx_ksys_write+0x10/0x10 do_syscall_64+0x115/0x690 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0fbea15907 Code: 10 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24 RSP: 002b:00007ffe22346ea8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000058 RCX: 00007f0fbea15907 RDX: 0000000000000058 RSI: 0000563ace6c0ef0 RDI: 0000000000000001 RBP: 0000563ace6c0ef0 R08: 0000563ace6c0ef0 R09: 6b6435726d694141 R10: 5250337279762f78 R11: 0000000000000246 R12: 0000000000000058 R13: 00007f0fbeb1c780 R14: ff1100000c480700 R15: ff1100000c480004 With this fix applied, rerunning the reproducer over fail-nth=1..256 yields no KASAN reports. [ idryomov: rename err_out_device_del -> err_out_device ] Cc: stable@vger.kernel.org Fixes: 27c97abc30e2 ("rbd: add add_disk() error handling") Signed-off-by: Zilin Guan Signed-off-by: Dawei Feng Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

rbd: check for EOD after exclusive lock is ensured to be held

2026-02-11T12:40:16+00:00

commit bd3884a204c3b507e6baa9a4091aa927f9af5404 upstream. Similar to commit 870611e4877e ("rbd: get snapshot context after exclusive lock is ensured to be held"), move the "beyond EOD" check into the image request state machine so that it's performed after exclusive lock is ensured to be held. This avoids various race conditions which can arise when the image is shrunk under I/O (in practice, mostly readahead). In one such scenario rbd_assert(objno < rbd_dev->object_map_size); can be triggered if a close-to-EOD read gets queued right before the shrink is initiated and the EOD check is performed against an outdated mapping_size. After the resize is done on the server side and exclusive lock is (re)acquired bringing along the new (now shrunk) object map, the read starts going through the state machine and rbd_obj_may_exist() gets invoked on an object that is out of bounds of rbd_dev->object_map array. Cc: stable@vger.kernel.org Signed-off-by: Ilya Dryomov Reviewed-by: Dongsheng Yang Signed-off-by: Greg Kroah-Hartman

Merge tag 'ceph-for-6.11-rc1' of https://github.com/ceph/ceph-client

2024-07-26T17:34:42+00:00

Pull ceph updates from Ilya Dryomov: "A small patchset to address bogus I/O errors and ultimately an assertion failure in the face of watch errors with -o exclusive mappings in RBD marked for stable and some assorted CephFS fixes" * tag 'ceph-for-6.11-rc1' of https://github.com/ceph/ceph-client: rbd: don't assume rbd_is_lock_owner() for exclusive mappings rbd: don't assume RBD_LOCK_STATE_LOCKED for exclusive mappings rbd: rename RBD_LOCK_STATE_RELEASING and releasing_wait ceph: fix incorrect kmalloc size of pagevec mempool ceph: periodically flush the cap releases ceph: convert comma to semicolon in __ceph_dentry_dir_lease_touch() ceph: use cap_wait_list only if debugfs is enabled

rbd: don't assume rbd_is_lock_owner() for exclusive mappings

2024-07-25T10:18:29+00:00

Expanding on the previous commit, assuming that rbd_is_lock_owner() always returns true (i.e. that we are either in RBD_LOCK_STATE_LOCKED or RBD_LOCK_STATE_QUIESCING) if the mapping is exclusive is wrong too. In case ceph_cls_set_cookie() fails, the lock would be temporarily released even if the mapping is exclusive, meaning that we can end up even in RBD_LOCK_STATE_UNLOCKED. IOW, exclusive mappings are really "just" about disabling automatic lock transitions (as documented in the man page), not about grabbing the lock and holding on to it whatever it takes. Cc: stable@vger.kernel.org Fixes: 637cd060537d ("rbd: new exclusive lock wait/wake code") Signed-off-by: Ilya Dryomov Reviewed-by: Dongsheng Yang

rbd: don't assume RBD_LOCK_STATE_LOCKED for exclusive mappings

2024-07-25T10:18:28+00:00

Every time a watch is reestablished after getting lost, we need to update the cookie which involves quiescing exclusive lock. For this, we transition from RBD_LOCK_STATE_LOCKED to RBD_LOCK_STATE_QUIESCING roughly for the duration of rbd_reacquire_lock() call. If the mapping is exclusive and I/O happens to arrive in this time window, it's failed with EROFS (later translated to EIO) based on the wrong assumption in rbd_img_exclusive_lock() -- "lock got released?" check there stopped making sense with commit a2b1da09793d ("rbd: lock should be quiesced on reacquire"). To make it worse, any such I/O is added to the acquiring list before EROFS is returned and this sets up for violating rbd_lock_del_request() precondition that the request is either on the running list or not on any list at all -- see commit ded080c86b3f ("rbd: don't move requests to the running list on errors"). rbd_lock_del_request() ends up processing these requests as if they were on the running list which screws up quiescing_wait completion counter and ultimately leads to rbd_assert(!completion_done(&rbd_dev->quiescing_wait)); being triggered on the next watch error. Cc: stable@vger.kernel.org # 06ef84c4e9c4: rbd: rename RBD_LOCK_STATE_RELEASING and releasing_wait Cc: stable@vger.kernel.org Fixes: 637cd060537d ("rbd: new exclusive lock wait/wake code") Signed-off-by: Ilya Dryomov Reviewed-by: Dongsheng Yang

rbd: rename RBD_LOCK_STATE_RELEASING and releasing_wait

2024-07-25T10:18:01+00:00

... to RBD_LOCK_STATE_QUIESCING and quiescing_wait to recognize that this state and the associated completion are backing rbd_quiesce_lock(), which isn't specific to releasing the lock. While exclusive lock does get quiesced before it's released, it also gets quiesced before an attempt to update the cookie is made and there the lock is not released as long as ceph_cls_set_cookie() succeeds. Signed-off-by: Ilya Dryomov Reviewed-by: Dongsheng Yang

block: move the stable_writes flag to queue_limits

2024-06-19T13:58:28+00:00

Move the stable_writes flag into the queue_limits feature field so that it can be set atomically with the queue frozen. The flag is now inherited by blk_stack_limits, which greatly simplifies the code in dm, and fixed md which previously did not pass on the flag set on lower devices. Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: Hannes Reinecke Link: https://lore.kernel.org/r/20240617060532.127975-18-hch@lst.de Signed-off-by: Jens Axboe

block: move the nonrot flag to queue_limits

2024-06-19T13:58:28+00:00

Move the nonrot flag into the queue_limits feature field so that it can be set atomically with the queue frozen. Use the chance to switch to defaulting to non-rotational and require the driver to opt into rotational, which matches the polarity of the sysfs interface. For the z2ram, ps3vram, 2x memstick, ubiblock and dcssblk the new rotational flag is not set as they clearly are not rotational despite this being a behavior change. There are some other drivers that unconditionally set the rotational flag to keep the existing behavior as they arguably can be used on rotational devices even if that is probably not their main use today (e.g. virtio_blk and drbd). The flag is automatically inherited in blk_stack_limits matching the existing behavior in dm and md. Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: Hannes Reinecke Link: https://lore.kernel.org/r/20240617060532.127975-15-hch@lst.de Signed-off-by: Jens Axboe

block: take io_opt and io_min into account for max_sectors

2024-06-14T16:19:44+00:00

The soft max_sectors limit is normally capped by the hardware limits and an arbitrary upper limit enforced by the kernel, but can be modified by the user. A few drivers want to increase this limit (nbd, rbd) or adjust it up or down based on hardware capabilities (sd). Change blk_validate_limits to default max_sectors to the optimal I/O size, or upgrade it to the preferred minimal I/O size if that is larger than the kernel default if no optimal I/O size is provided based on the logic in the SD driver. This keeps the existing kernel default for drivers that do not provide an io_opt or very big io_min value, but picks a much more useful default for those who provide these hints, and allows to remove the hacks to set the user max_sectors limit in nbd, rbd and sd. Signed-off-by: Christoph Hellwig Reviewed-by: Bart Van Assche Reviewed-by: Damien Le Moal Acked-by: Ilya Dryomov Reviewed-by: Martin K. Petersen Link: https://lore.kernel.org/r/20240531074837.1648501-5-hch@lst.de Signed-off-by: Jens Axboe