==================================================================
BUG: KASAN: use-after-free in dma_direct_unmap_sg+0xd4/0x51c kernel/dma/direct.c:471
Read of size 8 at addr ffff0000f7d8c010 by task kworker/u4:7/4745

CPU: 0 PID: 4745 Comm: kworker/u4:7 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
Workqueue: nvme-reset-wq nvme_reset_work
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351
 dma_direct_unmap_sg+0xd4/0x51c kernel/dma/direct.c:471
 dma_unmap_sg_attrs+0xcc/0xf8 kernel/dma/mapping.c:289
 dma_unmap_sgtable include/linux/dma-mapping.h:374 [inline]
 nvme_unmap_data+0x18c/0x7c0 drivers/nvme/host/pci.c:576
 nvme_pci_unmap_rq drivers/nvme/host/pci.c:1019 [inline]
 nvme_pci_complete_rq+0x218/0x348 drivers/nvme/host/pci.c:1024
 nvme_handle_cqe drivers/nvme/host/pci.c:1088 [inline]
 nvme_poll_cq+0x578/0xf50 drivers/nvme/host/pci.c:1115
 nvme_reap_pending_cqes drivers/nvme/host/pci.c:1562 [inline]
 nvme_dev_disable+0x350/0x5ec drivers/nvme/host/pci.c:2769
 nvme_reset_work+0x128/0x477c drivers/nvme/host/pci.c:2889
 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292
 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850

Allocated by task 52:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:936 [inline]
 __kmalloc+0xd8/0x180 mm/slab_common.c:949
 kmalloc include/linux/slab.h:568 [inline]
 mempool_kmalloc+0x28/0x38 mm/mempool.c:550
 mempool_alloc+0x154/0x3e0 mm/mempool.c:412
 nvme_map_data drivers/nvme/host/pci.c:841 [inline]
 nvme_prep_rq+0x7d4/0x22fc drivers/nvme/host/pci.c:900
 nvme_queue_rq+0xe4/0x698 drivers/nvme/host/pci.c:943
 blk_mq_dispatch_rq_list+0xc6c/0x1d3c block/blk-mq.c:2088
 __blk_mq_sched_dispatch_requests+0x384/0x3c4 block/blk-mq-sched.c:318
 blk_mq_sched_dispatch_requests+0xcc/0x17c block/blk-mq-sched.c:338
 __blk_mq_run_hw_queue+0x1d8/0x2b0 block/blk-mq.c:2208
 blk_mq_run_work_fn+0x60/0xb0 block/blk-mq.c:2522
 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292
 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850

Freed by task 52:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516
 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237
 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xbc/0x21c mm/slub.c:3700
 kfree+0xd0/0x1a8 mm/slab_common.c:988
 mempool_kfree+0x20/0x30 mm/mempool.c:556
 mempool_free+0xc0/0x2e4 mm/mempool.c:521
 nvme_unmap_data+0x684/0x7c0 drivers/nvme/host/pci.c:585
 nvme_pci_unmap_rq drivers/nvme/host/pci.c:1019 [inline]
 nvme_pci_complete_rq+0x218/0x348 drivers/nvme/host/pci.c:1024
 blk_mq_complete_request+0x94/0xa8 block/blk-mq.c:1237
 nvme_cancel_request+0xa0/0x1bc drivers/nvme/host/core.c:466
 bt_tags_iter+0x28c/0x3b8 block/blk-mq-tag.c:365
 __sbitmap_for_each_set include/linux/sbitmap.h:286 [inline]
 sbitmap_for_each_set+0x2b8/0x558 include/linux/sbitmap.h:307
 bt_tags_for_each block/blk-mq-tag.c:394 [inline]
 __blk_mq_all_tag_iter block/blk-mq-tag.c:405 [inline]
 blk_mq_tagset_busy_iter+0x224/0x300 block/blk-mq-tag.c:449
 nvme_cancel_tagset+0x60/0x98 drivers/nvme/host/core.c:474
 nvme_dev_disable+0x39c/0x5ec drivers/nvme/host/pci.c:2771
 nvme_timeout+0x628/0xa88 drivers/nvme/host/pci.c:-1
 blk_mq_rq_timed_out block/blk-mq.c:1566 [inline]
 blk_mq_handle_expired+0x148/0x270 block/blk-mq.c:1634
 bt_iter+0x2e4/0x3bc block/blk-mq-tag.c:295
 __sbitmap_for_each_set include/linux/sbitmap.h:286 [inline]
 sbitmap_for_each_set+0x2b8/0x558 include/linux/sbitmap.h:307
 bt_for_each block/blk-mq-tag.c:327 [inline]
 blk_mq_queue_tag_busy_iter+0x440/0x730 block/blk-mq-tag.c:536
 blk_mq_timeout_work+0x16c/0x300 block/blk-mq.c:1676
 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292
 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850

The buggy address belongs to the object at ffff0000f7d8c000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 16 bytes inside of
 4096-byte region [ffff0000f7d8c000, ffff0000f7d8d000)

The buggy address belongs to the physical page:
page:000000003b89b16f refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x137d88
head:000000003b89b16f order:3 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 fffffc0003669600 dead000000000002 ffff0000c0002a80
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000f7d8bf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000f7d8bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000f7d8c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff0000f7d8c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000f7d8c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Unable to handle kernel paging request at virtual address dfff800000000031
KASAN: null-ptr-deref in range [0x0000000000000188-0x000000000000018f]
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
[dfff800000000031] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4745 Comm: kworker/u4:7 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
Workqueue: nvme-reset-wq nvme_reset_work
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : blk_mq_complete_request_remote+0x78/0x61c block/blk-mq.c:1210
lr : blk_mq_complete_request_remote+0x2c/0x61c block/blk-mq.c:1202
sp : ffff800021ae7560
x29: ffff800021ae7560 x28: 1fffe00019f93078 x27: 0000000000000003
x26: ffff0000cfe678c0 x25: ffff0000cfc983ea x24: dfff800000000000
x23: dfff800000000000 x22: ffff0000ce8ce458 x21: 1fffe00019fccf3e
x20: 000000000000018e x19: ffff0000cfe678c0 x18: 1fffe00033e6db7e
x17: ffff8000153bd000 x16: ffff800011bb65f8 x15: ffff00019f36dbfc
x14: 0000000000000001 x13: 1fffe00019f38900 x12: 0000000000000000
x11: ff0080000a7c749c x10: 0000000000000000 x9 : 1fffe00019fccf1a
x8 : 0000000000000031 x7 : 0000000000000000 x6 : ffff80000a7a5f3c
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff80000a7a0298
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0000cfe678c0
Call trace:
 blk_mq_complete_request_remote+0x78/0x61c block/blk-mq.c:1210
 nvme_try_complete_req drivers/nvme/host/nvme.h:708 [inline]
 nvme_handle_cqe drivers/nvme/host/pci.c:1085 [inline]
 nvme_poll_cq+0x518/0xf50 drivers/nvme/host/pci.c:1115
 nvme_reap_pending_cqes drivers/nvme/host/pci.c:1562 [inline]
 nvme_dev_disable+0x350/0x5ec drivers/nvme/host/pci.c:2769
 nvme_reset_work+0x128/0x477c drivers/nvme/host/pci.c:2889
 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292
 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850
Code: 9784bafd f9400288 91063914 d343fe88 (38f76908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	9784bafd 	bl	0xfffffffffe12ebf4
   4:	f9400288 	ldr	x8, [x20]
   8:	91063914 	add	x20, x8, #0x18e
   c:	d343fe88 	lsr	x8, x20, #3
* 10:	38f76908 	ldrsb	w8, [x8, x23] <-- trapping instruction