================================================================== BUG: KASAN: use-after-free in disk_unblock_events+0x55/0x60 block/genhd.c:1543 Read of size 8 at addr ffff8800b6f7e2e8 by task syz-executor280/2094 CPU: 0 PID: 2094 Comm: syz-executor280 Not tainted 4.4.174+ #17 0000000000000000 933f5ee786ab420f ffff8800b65af6c0 ffffffff81aad1a1 0000000000000000 ffffea0002dbde00 ffff8800b6f7e2e8 0000000000000008 0000000000000000 ffff8800b65af6f8 ffffffff81490120 0000000000000000 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [] print_address_description+0x6f/0x21b mm/kasan/report.c:252 [] kasan_report_error mm/kasan/report.c:351 [inline] [] kasan_report mm/kasan/report.c:408 [inline] [] kasan_report.cold+0x8c/0x2be mm/kasan/report.c:393 [] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429 [] disk_unblock_events+0x55/0x60 block/genhd.c:1543 [] __blkdev_get+0x70c/0xdf0 fs/block_dev.c:1297 [] blkdev_get+0x2e8/0x920 fs/block_dev.c:1353 [] blkdev_open+0x1aa/0x250 fs/block_dev.c:1508 [] do_dentry_open+0x38f/0xbd0 fs/open.c:749 [] vfs_open+0x10b/0x210 fs/open.c:862 [] do_last fs/namei.c:3269 [inline] [] path_openat+0x136f/0x4470 fs/namei.c:3406 [] do_filp_open+0x1a1/0x270 fs/namei.c:3440 [] do_sys_open+0x2f8/0x600 fs/open.c:1038 [] C_SYSC_open fs/compat.c:1092 [inline] [] compat_SyS_open+0x2a/0x40 fs/compat.c:1090 [] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] [] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397 [] sysenter_flags_fixed+0xd/0x1a Allocated by task 2094: [] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [] save_stack mm/kasan/kasan.c:512 [inline] [] set_track mm/kasan/kasan.c:524 [inline] [] kasan_kmalloc.part.0+0x62/0xf0 mm/kasan/kasan.c:616 [] kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:601 [] kmem_cache_alloc_trace+0x123/0x2d0 mm/slub.c:2642 [] kmem_cache_alloc_node_trace include/linux/slab.h:367 [inline] [] kmalloc_node include/linux/slab.h:514 [inline] [] kzalloc_node include/linux/slab.h:631 [inline] [] alloc_disk_node+0x50/0x3c0 block/genhd.c:1282 [] alloc_disk+0x1b/0x20 block/genhd.c:1274 [] loop_add+0x380/0x830 drivers/block/loop.c:1857 [] loop_control_ioctl+0x138/0x2f0 drivers/block/loop.c:1988 [] C_SYSC_ioctl fs/compat_ioctl.c:1592 [inline] [] compat_SyS_ioctl+0x403/0x2210 fs/compat_ioctl.c:1544 [] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] [] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397 [] sysenter_flags_fixed+0xd/0x1a Freed by task 2094: [] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [] save_stack mm/kasan/kasan.c:512 [inline] [] set_track mm/kasan/kasan.c:524 [inline] [] kasan_slab_free+0xb0/0x190 mm/kasan/kasan.c:589 [] slab_free_hook mm/slub.c:1383 [inline] [] slab_free_freelist_hook mm/slub.c:1405 [inline] [] slab_free mm/slub.c:2859 [inline] [] kfree+0xf4/0x310 mm/slub.c:3749 [] disk_release+0x255/0x330 block/genhd.c:1118 [] device_release+0x7d/0x220 drivers/base/core.c:247 [] kobject_cleanup lib/kobject.c:643 [inline] [] kobject_release lib/kobject.c:672 [inline] [] kref_sub include/linux/kref.h:73 [inline] [] kref_put include/linux/kref.h:98 [inline] [] kobject_put+0x14c/0x260 lib/kobject.c:689 [] put_disk+0x23/0x30 block/genhd.c:1346 [] __blkdev_get+0x66c/0xdf0 fs/block_dev.c:1290 [] blkdev_get+0x2e8/0x920 fs/block_dev.c:1353 [] blkdev_open+0x1aa/0x250 fs/block_dev.c:1508 [] do_dentry_open+0x38f/0xbd0 fs/open.c:749 [] vfs_open+0x10b/0x210 fs/open.c:862 [] do_last fs/namei.c:3269 [inline] [] path_openat+0x136f/0x4470 fs/namei.c:3406 [] do_filp_open+0x1a1/0x270 fs/namei.c:3440 [] do_sys_open+0x2f8/0x600 fs/open.c:1038 [] C_SYSC_open fs/compat.c:1092 [inline] [] compat_SyS_open+0x2a/0x40 fs/compat.c:1090 [] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] [] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397 [] sysenter_flags_fixed+0xd/0x1a The buggy address belongs to the object at ffff8800b6f7dd80 which belongs to the cache kmalloc-2048 of size 2048 The buggy address is located 1384 bytes inside of 2048-byte region [ffff8800b6f7dd80, ffff8800b6f7e580) The buggy address belongs to the page: kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN Modules linked in: CPU: 1 PID: -1225269888 Comm: @‡¶ Not tainted 4.4.174+ #17 task: ffff8800b61a8000 task.stack: ffffffff8142ac50 RIP: 0010:[] [] constant_test_bit arch/x86/include/asm/bitops.h:311 [inline] RIP: 0010:[] [] PageSlab include/linux/page-flags.h:217 [inline] RIP: 0010:[] [] page_mapcount include/linux/mm.h:464 [inline] RIP: 0010:[] [] dump_page_badflags+0x30/0x70 mm/debug.c:85 RSP: 0018:ffff8800b614f410 EFLAGS: 00010007 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000360adf29f RSI: ffffffff8142abdf RDI: 0000001b056f94fe RBP: ffff8800b614f440 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffff83fdf193 R12: 0000001b056f94fe R13: ffffffff82891be0 R14: 00000000000008fd R15: fffffbfff092dca5 FS: 0000000000000000(0000) GS:ffff8801db700000(0063) knlGS:00000000087cf840 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: ffff8800b6537a00 CR3: 00000000b6fe5000 CR4: 00000000001606b0 Stack: ffff8800b614f450 0000001b056f9cd8 0000001b056f94fe ffffffff82891be0 00000000000008fd fffffbfff092dca5 ffff8800b614f460 ffffffff8142ac50 0000001b056f94fe 0000000000000001 ffff8800b614f4a0 ffffffff8142ac16 Call Trace: Code: 57 41 56 41 55 49 89 f5 41 54 49 89 fc 53 48 89 d3 48 83 ec 08 e8 11 ea ed ff 4c 89 e2 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 75 22 49 8b 04 24 a8 80 0f 84 fa 34 06 00 e8 e9 e9 RIP [] constant_test_bit arch/x86/include/asm/bitops.h:311 [inline] RIP [] PageSlab include/linux/page-flags.h:217 [inline] RIP [] page_mapcount include/linux/mm.h:464 [inline] RIP [] dump_page_badflags+0x30/0x70 mm/debug.c:85 RSP ---[ end trace 3c6aec468e5d4d6f ]---