Hello, Thanks for your report! On Fri, Jun 7, 2019 at 4:16 AM syzbot <syzbot+784281a934c3f71eb71a@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: 9221dced Merge tag 'for-linus-20190601' of git://git.kerne.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=16b3b772a00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=1fa7e451a5cac069 > dashboard link: https://syzkaller.appspot.com/bug?extid=784281a934c3f71eb71a > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=149089aaa00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11b24edea00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+784281a934c3f71eb71a@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KASAN: use-after-free in blk_mq_free_rqs+0x49f/0x4b0 > block/blk-mq.c:2049 > Read of size 8 at addr ffff88809b5c0b10 by task kworker/1:1/22 > > CPU: 1 PID: 22 Comm: kworker/1:1 Not tainted 5.2.0-rc2+ #17 > 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+0x7c/0x20d mm/kasan/report.c:188 > __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 > 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 8904: > 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:3555 > kmalloc include/linux/slab.h:547 [inline] > kzalloc include/linux/slab.h:742 [inline] > loop_add+0x51/0x8d0 drivers/block/loop.c:1973 > loop_control_ioctl drivers/block/loop.c:2157 [inline] > loop_control_ioctl+0x165/0x360 drivers/block/loop.c:2139 > vfs_ioctl fs/ioctl.c:46 [inline] > file_ioctl fs/ioctl.c:509 [inline] > do_vfs_ioctl+0xd5f/0x1380 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 > > Freed by task 8905: > 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:3432 [inline] > kfree+0xcf/0x220 mm/slab.c:3755 > 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+0xd5f/0x1380 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 ffff88809b5c0900 > which belongs to the cache kmalloc-1k of size 1024 > The buggy address is located 528 bytes inside of > 1024-byte region [ffff88809b5c0900, ffff88809b5c0d00) > The buggy address belongs to the page: > page:ffffea00026d7000 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 > index:0x0 compound_mapcount: 0 > flags: 0x1fffc0000010200(slab|head) > raw: 01fffc0000010200 ffffea0002411188 ffffea000290c088 ffff8880aa400ac0 > raw: 0000000000000000 ffff88809b5c0000 0000000100000007 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff88809b5c0a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff88809b5c0a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff88809b5c0b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff88809b5c0b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff88809b5c0c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== It should be fixed by the following patch: https://lore.kernel.org/linux-block/20190606144714.GA6549@t480-pf1aa2c2/T/#m0a3d000613bcfd5271a0748ff230a4eccb2d65f1 Thanks, Ming Lei
