================================================================== BUG: KASAN: use-after-free in get_disk_and_module block/genhd.c:1524 [inline] BUG: KASAN: use-after-free in exact_lock+0x34/0xc0 block/genhd.c:594 Read of size 8 at addr ffff8881f04b14d0 by task syz.0.2517/11020 CPU: 1 PID: 11020 Comm: syz.0.2517 Tainted: G W 5.4.290-syzkaller-00017-g6b07fcd94a6a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d8/0x241 lib/dump_stack.c:118 print_address_description+0x8c/0x600 mm/kasan/report.c:384 __kasan_report+0xf3/0x120 mm/kasan/report.c:516 kasan_report+0x30/0x60 mm/kasan/common.c:653 get_disk_and_module block/genhd.c:1524 [inline] exact_lock+0x34/0xc0 block/genhd.c:594 kobj_lookup+0x2a3/0x450 drivers/base/map.c:119 get_gendisk+0xd7/0x370 block/genhd.c:879 bdev_get_gendisk fs/block_dev.c:1105 [inline] __blkdev_get+0x166/0x1160 fs/block_dev.c:1560 blkdev_get+0x2de/0x3a0 fs/block_dev.c:1714 do_dentry_open+0x964/0x1130 fs/open.c:806 do_last fs/namei.c:3565 [inline] path_openat+0x29bf/0x34b0 fs/namei.c:3683 do_filp_open+0x20b/0x450 fs/namei.c:3713 do_sys_open+0x39c/0x810 fs/open.c:1123 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 RIP: 0033:0x7f385471b169 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3852d85038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f3854933fa0 RCX: 00007f385471b169 RDX: 0000000000000000 RSI: 0000400000004280 RDI: ffffffffffffff9c RBP: 00007f385479c2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f3854933fa0 R15: 00007ffe93be6e68 Allocated by task 1: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] __kasan_kmalloc+0x171/0x210 mm/kasan/common.c:529 kmem_cache_alloc_node_trace include/linux/slab.h:444 [inline] kmalloc_node include/linux/slab.h:594 [inline] kzalloc_node include/linux/slab.h:701 [inline] __alloc_disk_node+0x76/0x5a0 block/genhd.c:1477 loop_add+0x315/0x740 drivers/block/loop.c:2142 loop_init+0x225/0x263 drivers/block/loop.c:2387 do_one_initcall+0x186/0x6d0 init/main.c:1192 do_initcall_level+0x213/0x41e init/main.c:1259 do_initcalls+0x49/0x86 init/main.c:1275 kernel_init_freeable+0x2b9/0x466 init/main.c:1458 kernel_init+0xd/0x380 init/main.c:1375 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354 Freed by task 10629: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] kasan_set_free_info mm/kasan/common.c:345 [inline] __kasan_slab_free+0x1b5/0x270 mm/kasan/common.c:487 slab_free_hook mm/slub.c:1455 [inline] slab_free_freelist_hook mm/slub.c:1494 [inline] slab_free mm/slub.c:3080 [inline] kfree+0x123/0x370 mm/slub.c:4071 device_release+0x6b/0x190 drivers/base/core.c:1776 kobject_cleanup lib/kobject.c:716 [inline] kobject_release lib/kobject.c:747 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1e6/0x2f0 lib/kobject.c:764 loop_remove+0x8f/0xa0 drivers/block/loop.c:2197 loop_control_ioctl+0x564/0x620 drivers/block/loop.c:2293 do_vfs_ioctl+0x742/0x1720 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 The buggy address belongs to the object at ffff8881f04b1000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 1232 bytes inside of 2048-byte region [ffff8881f04b1000, ffff8881f04b1800) The buggy address belongs to the page: page:ffffea0007c12c00 refcount:1 mapcount:0 mapping:ffff8881f5c0c000 index:0x0 compound_mapcount: 0 flags: 0x8000000000010200(slab|head) raw: 8000000000010200 ffffea00078fe400 0000000300000003 ffff8881f5c0c000 raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC) set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook mm/page_alloc.c:2165 [inline] prep_new_page+0x18f/0x370 mm/page_alloc.c:2171 get_page_from_freelist+0x2d13/0x2d90 mm/page_alloc.c:3794 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4893 alloc_slab_page+0x39/0x3c0 mm/slub.c:343 allocate_slab mm/slub.c:1683 [inline] new_slab+0x97/0x440 mm/slub.c:1749 new_slab_objects mm/slub.c:2505 [inline] ___slab_alloc+0x2fe/0x490 mm/slub.c:2667 __slab_alloc+0x62/0xa0 mm/slub.c:2707 slab_alloc_node mm/slub.c:2792 [inline] slab_alloc mm/slub.c:2837 [inline] kmem_cache_alloc_trace+0x12d/0x260 mm/slub.c:2854 kmem_cache_alloc_node_trace include/linux/slab.h:444 [inline] kmalloc_node include/linux/slab.h:594 [inline] kzalloc_node include/linux/slab.h:701 [inline] __alloc_disk_node+0x76/0x5a0 block/genhd.c:1477 brd_alloc+0x17b/0x430 drivers/block/brd.c:394 brd_init+0x120/0x427 drivers/block/brd.c:518 do_one_initcall+0x186/0x6d0 init/main.c:1192 do_initcall_level+0x213/0x41e init/main.c:1259 do_initcalls+0x49/0x86 init/main.c:1275 kernel_init_freeable+0x2b9/0x466 init/main.c:1458 kernel_init+0xd/0x380 init/main.c:1375 page_owner free stack trace missing Memory state around the buggy address: ffff8881f04b1380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881f04b1400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881f04b1480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881f04b1500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881f04b1580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== incfs: Error accessing: ./file0. incfs: mount failed -20