================================================================== BUG: KASAN: use-after-free in blk_mq_free_rqs+0x49f/0x4b0 block/blk-mq.c:2049 Read of size 8 at addr ffff8882191a8fd0 by task kworker/0:2/3008 CPU: 0 PID: 3008 Comm: kworker/0:2 Not tainted 5.2.0-rc3-next-20190607 #11 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events __blk_release_queue Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482 kasan_report+0x12/0x20 mm/kasan/common.c:614 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 blk_mq_free_rqs+0x49f/0x4b0 block/blk-mq.c:2049 blk_mq_sched_free_tags block/blk-mq-sched.c:453 [inline] blk_mq_sched_tags_teardown+0x126/0x210 block/blk-mq-sched.c:485 blk_mq_exit_sched+0x1fa/0x2d0 block/blk-mq-sched.c:557 elevator_exit+0x70/0xa0 block/elevator.c:185 blk_exit_queue block/blk-sysfs.c:853 [inline] __blk_release_queue+0x127/0x330 block/blk-sysfs.c:895 process_one_work+0x989/0x1790 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x354/0x420 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Allocated by task 1: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_kmalloc mm/kasan/common.c:489 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503 kmem_cache_alloc_trace+0x151/0x750 mm/slab.c:3549 kmalloc include/linux/slab.h:547 [inline] kzalloc include/linux/slab.h:742 [inline] loop_add+0x51/0x8d0 drivers/block/loop.c:1973 loop_init+0x1fe/0x25a drivers/block/loop.c:2267 do_one_initcall+0x107/0x7ba init/main.c:915 do_initcall_level init/main.c:983 [inline] do_initcalls init/main.c:991 [inline] do_basic_setup init/main.c:1009 [inline] kernel_init_freeable+0x4d4/0x5c3 init/main.c:1169 kernel_init+0x12/0x1c5 init/main.c:1087 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Freed by task 24601: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459 __cache_free mm/slab.c:3426 [inline] kfree+0x106/0x2a0 mm/slab.c:3753 loop_remove+0xa1/0xd0 drivers/block/loop.c:2078 loop_control_ioctl drivers/block/loop.c:2173 [inline] loop_control_ioctl+0x320/0x360 drivers/block/loop.c:2139 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8882191a8dc0 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 528 bytes inside of 1024-byte region [ffff8882191a8dc0, ffff8882191a91c0) The buggy address belongs to the page: page:ffffea0008646a00 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0x0 compound_mapcount: 0 flags: 0x6fffc0000010200(slab|head) raw: 06fffc0000010200 ffffea0008662208 ffffea0008647208 ffff8880aa400ac0 raw: 0000000000000000 ffff8882191a8040 0000000100000007 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8882191a8e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8882191a8f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8882191a8f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8882191a9000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8882191a9080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================