Hello, syzbot found the following issue on: HEAD commit: 280d542f Merge tag 'drm-fixes-2021-03-05' of git://anongit.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15ade5aed00000 kernel config: https://syzkaller.appspot.com/x/.config?x=952047a9dbff6a6a dashboard link: https://syzkaller.appspot.com/bug?extid=8fede7e30c7cee0de139 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+8fede7e30c7cee0de139@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== BUG: KASAN: use-after-free in bdev_nr_sectors include/linux/genhd.h:266 [inline] BUG: KASAN: use-after-free in disk_part_iter_next+0x49d/0x530 block/genhd.c:207 Read of size 8 at addr ffff88804b0022e8 by task systemd-udevd/9804 CPU: 1 PID: 9804 Comm: systemd-udevd Not tainted 5.12.0-rc1-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0xfa/0x151 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2c6 mm/kasan/report.c:232 __kasan_report mm/kasan/report.c:399 [inline] kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416 bdev_nr_sectors include/linux/genhd.h:266 [inline] disk_part_iter_next+0x49d/0x530 block/genhd.c:207 blk_drop_partitions+0x10a/0x180 block/partitions/core.c:543 bdev_disk_changed+0x238/0x430 fs/block_dev.c:1237 __loop_clr_fd+0x7c7/0xff0 drivers/block/loop.c:1271 lo_release+0x1ac/0x1f0 drivers/block/loop.c:1923 __blkdev_put+0x54e/0x800 fs/block_dev.c:1579 blkdev_put+0x92/0x580 fs/block_dev.c:1632 blkdev_close+0x8c/0xb0 fs/block_dev.c:1640 __fput+0x288/0x920 fs/file_table.c:280 task_work_run+0xdd/0x1a0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f8141652270 Code: 73 01 c3 48 8b 0d 38 7d 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c1 20 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ee fb ff ff 48 89 04 24 RSP: 002b:00007ffe05d67588 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007f8141652270 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007 RBP: 00007f814250c710 R08: 000055e767969790 R09: 000055e767968300 R10: 00007f814250c8c0 R11: 0000000000000246 R12: 0000000000000000 R13: 000055e767979eb0 R14: 0000000000000003 R15: 000000000000000e Allocated by task 9582: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:427 [inline] __kasan_slab_alloc+0x73/0x90 mm/kasan/common.c:460 kasan_slab_alloc include/linux/kasan.h:223 [inline] slab_post_alloc_hook mm/slab.h:516 [inline] slab_alloc mm/slab.c:3325 [inline] kmem_cache_alloc+0x1c3/0x4f0 mm/slab.c:3502 bdev_alloc_inode+0x18/0x80 fs/block_dev.c:786 alloc_inode+0x61/0x230 fs/inode.c:234 new_inode_pseudo fs/inode.c:928 [inline] new_inode+0x27/0x2f0 fs/inode.c:957 bdev_alloc+0x20/0x2f0 fs/block_dev.c:876 add_partition+0x1ab/0x8a0 block/partitions/core.c:348 bdev_add_partition+0xb6/0x130 block/partitions/core.c:451 blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43 blkpg_ioctl block/ioctl.c:60 [inline] blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548 block_ioctl+0xf9/0x140 fs/block_dev.c:1658 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 8676: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357 ____kasan_slab_free mm/kasan/common.c:360 [inline] ____kasan_slab_free mm/kasan/common.c:325 [inline] __kasan_slab_free+0xc7/0x100 mm/kasan/common.c:367 kasan_slab_free include/linux/kasan.h:199 [inline] __cache_free mm/slab.c:3440 [inline] kmem_cache_free+0x6f/0x1d0 mm/slab.c:3733 i_callback+0x3f/0x70 fs/inode.c:223 rcu_do_batch kernel/rcu/tree.c:2559 [inline] rcu_core+0x722/0x1280 kernel/rcu/tree.c:2794 __do_softirq+0x29b/0x9f6 kernel/softirq.c:345 Last potentially related work creation: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_record_aux_stack+0xa4/0xd0 mm/kasan/generic.c:345 __call_rcu kernel/rcu/tree.c:3039 [inline] call_rcu+0xb1/0x700 kernel/rcu/tree.c:3114 destroy_inode+0x129/0x1b0 fs/inode.c:289 iput_final fs/inode.c:1654 [inline] iput.part.0+0x57e/0x810 fs/inode.c:1680 iput+0x58/0x70 fs/inode.c:1670 disk_part_iter_exit block/genhd.c:236 [inline] disk_part_iter_next+0x9a/0x530 block/genhd.c:203 blk_drop_partitions+0x10a/0x180 block/partitions/core.c:543 bdev_disk_changed+0x238/0x430 fs/block_dev.c:1237 loop_reread_partitions+0x29/0x50 drivers/block/loop.c:655 loop_set_status+0x704/0x1050 drivers/block/loop.c:1418 loop_set_status64 drivers/block/loop.c:1538 [inline] lo_ioctl+0x4ca/0x1620 drivers/block/loop.c:1706 blkdev_ioctl+0x2a1/0x6d0 block/ioctl.c:583 block_ioctl+0xf9/0x140 fs/block_dev.c:1658 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88804b0022c0 which belongs to the cache bdev_cache of size 2792 The buggy address is located 40 bytes inside of 2792-byte region [ffff88804b0022c0, ffff88804b002da8) The buggy address belongs to the page: page:00000000708f9251 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88804b002fff pfn:0x4b002 flags: 0x4fff00000000200(slab) raw: 04fff00000000200 ffffea00010ecd48 ffffea00012c2fc8 ffff888010b95700 raw: ffff88804b002fff ffff88804b0022c0 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88804b002180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88804b002200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88804b002280: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ^ ffff88804b002300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804b002380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This report is generated by a bot. 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