================================================================== BUG: KASAN: slab-use-after-free in snapshot_ctr+0x586/0x1350 drivers/md/dm-snap.c:1288 Read of size 8 at addr ffff88810c666998 by task syz.0.1/318 CPU: 1 UID: 0 PID: 318 Comm: syz.0.1 Not tainted syzkaller #0 1736d3b6ee88961c9d73e511fbf4428dbce80e3d Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026 Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:94 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120 print_address_description+0x71/0x210 mm/kasan/report.c:377 print_report+0x4a/0x70 mm/kasan/report.c:481 kasan_report+0x162/0x1a0 mm/kasan/report.c:594 __asan_report_load8_noabort+0x18/0x20 mm/kasan/report_generic.c:381 snapshot_ctr+0x586/0x1350 drivers/md/dm-snap.c:1288 dm_table_add_target+0x59c/0xcb0 drivers/md/dm-table.c:760 populate_table drivers/md/dm-ioctl.c:1494 [inline] table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536 ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline] dm_ctl_ioctl+0x8f3/0xde0 drivers/md/dm-ioctl.c:2129 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/common.c:47 [inline] do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f5aa4d9f559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5aa5bbc028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f5aa5025fa0 RCX: 00007f5aa4d9f559 RDX: 0000200000002b40 RSI: 00000000c138fd09 RDI: 0000000000000003 RBP: 00007f5aa4e36b50 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5aa5026038 R14: 00007f5aa5025fa0 R15: 00007ffe171f8138 Allocated by task 318: kasan_save_stack mm/kasan/common.c:49 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:70 kasan_save_alloc_info+0x3a/0x50 mm/kasan/generic.c:565 poison_kmalloc_redzone mm/kasan/common.c:379 [inline] __kasan_kmalloc+0x96/0xb0 mm/kasan/common.c:396 kasan_kmalloc include/linux/kasan.h:261 [inline] __kmalloc_cache_node_noprof+0x225/0x430 mm/slub.c:4440 kmalloc_node_noprof include/linux/slab.h:1004 [inline] open_table_device drivers/md/dm.c:758 [inline] dm_get_table_device+0x1e3/0x6c0 drivers/md/dm.c:837 dm_get_device+0x32b/0x7f0 drivers/md/dm-table.c:394 snapshot_ctr+0x292/0x1350 drivers/md/dm-snap.c:1273 dm_table_add_target+0x59c/0xcb0 drivers/md/dm-table.c:760 populate_table drivers/md/dm-ioctl.c:1494 [inline] table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536 ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline] dm_ctl_ioctl+0x8f3/0xde0 drivers/md/dm-ioctl.c:2129 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/common.c:47 [inline] do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78 entry_SYSCALL_64_after_hwframe+0x76/0x7e Freed by task 318: kasan_save_stack mm/kasan/common.c:49 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:70 kasan_save_free_info+0x44/0x50 mm/kasan/generic.c:579 poison_slab_object mm/kasan/common.c:249 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:266 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2445 [inline] slab_free mm/slub.c:4716 [inline] kfree+0x158/0x440 mm/slub.c:4877 close_table_device drivers/md/dm.c:814 [inline] dm_put_table_device+0x298/0x2e0 drivers/md/dm.c:857 upgrade_mode drivers/md/dm-table.c:328 [inline] dm_get_device+0x571/0x7f0 drivers/md/dm-table.c:405 snapshot_ctr+0x435/0x1350 drivers/md/dm-snap.c:1283 dm_table_add_target+0x59c/0xcb0 drivers/md/dm-table.c:760 populate_table drivers/md/dm-ioctl.c:1494 [inline] table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536 ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline] dm_ctl_ioctl+0x8f3/0xde0 drivers/md/dm-ioctl.c:2129 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/common.c:47 [inline] do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78 entry_SYSCALL_64_after_hwframe+0x76/0x7e The buggy address belongs to the object at ffff88810c666980 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 24 bytes inside of freed 96-byte region [ffff88810c666980, ffff88810c6669e0) The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10c666 flags: 0x4000000000000000(zone=1) page_type: f5(slab) raw: 4000000000000000 ffff888100041280 ffffea0004319bc0 dead000000000002 raw: 0000000000000000 0000000080200020 00000001f5000000 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0), ts 2831903552, free_ts 1998047334 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook+0x37d/0x3b0 mm/page_alloc.c:1864 prep_new_page+0x2d/0x180 mm/page_alloc.c:1872 get_page_from_freelist+0x4aea/0x4ba0 mm/page_alloc.c:3949 __alloc_pages_noprof+0x35a/0x7e0 mm/page_alloc.c:5316 alloc_slab_page+0x6b/0x1e0 mm/slub.c:-1 allocate_slab+0x69/0x430 mm/slub.c:2687 new_slab mm/slub.c:2741 [inline] ___slab_alloc+0x591/0x8c0 mm/slub.c:3934 __slab_alloc mm/slub.c:4025 [inline] __slab_alloc_node mm/slub.c:4078 [inline] slab_alloc_node mm/slub.c:4241 [inline] __kmalloc_cache_noprof+0x2cd/0x470 mm/slub.c:4423 kmalloc_noprof include/linux/slab.h:882 [inline] kzalloc_noprof include/linux/slab.h:1117 [inline] call_usermodehelper_setup+0x97/0x300 kernel/umh.c:363 kobject_uevent_env+0x65f/0x7e0 lib/kobject_uevent.c:628 kobject_uevent+0x21/0x40 lib/kobject_uevent.c:656 kset_register+0x1bc/0x250 lib/kobject.c:877 bus_register+0x184/0x4d0 drivers/base/bus.c:884 scsi_sysfs_register+0x1c/0x80 drivers/scsi/scsi_sysfs.c:570 init_scsi+0x51/0xd0 drivers/scsi/scsi.c:1025 do_one_initcall+0x1e8/0x6a0 init/main.c:1406 page last free pid 1 tgid 1 stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1391 [inline] __free_pages_ok+0xc5d/0xf30 mm/page_alloc.c:1548 free_unref_page+0x466/0xf50 mm/page_alloc.c:2873 __folio_put+0x272/0x2c0 mm/swap.c:115 folio_put include/linux/mm.h:1596 [inline] free_large_kmalloc+0xb7/0x110 mm/slub.c:4844 kfree+0x209/0x440 mm/slub.c:4871 kvfree+0x39/0x50 mm/util.c:716 btf_add_type kernel/bpf/btf.c:1729 [inline] btf_check_all_metas+0x60b/0xbd0 kernel/bpf/btf.c:5326 btf_parse_base+0x36d/0x6e0 kernel/bpf/btf.c:6295 btf_parse_vmlinux+0xb6/0x3b0 kernel/bpf/btf.c:6329 bpf_get_btf_vmlinux+0x45/0x70 kernel/bpf/verifier.c:22683 btf_get_module_btf+0x85/0x200 kernel/bpf/btf.c:8291 __register_btf_kfunc_id_set+0xbe/0x1f10 kernel/bpf/btf.c:8710 register_btf_kfunc_id_set+0xaa/0xf0 kernel/bpf/btf.c:8745 wakeup_sources_bpf_init+0x1b/0x65 drivers/base/power/wakeup.c:1332 wakeup_sources_init+0x2e/0x4b drivers/base/power/wakeup.c:1343 do_one_initcall+0x1e8/0x6a0 init/main.c:1406 Memory state around the buggy address: ffff88810c666880: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88810c666900: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc >ffff88810c666980: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff88810c666a00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88810c666a80: 00 00 00 00 00 00 00 00 03 fc fc fc fc fc fc fc ================================================================== device-mapper: table: 252:0: device 1:0 not in table devices list device-mapper: table: 252:0: snapshot-merge: COW device cannot be the same as origin device (-EINVAL) device-mapper: ioctl: error adding target to table device-mapper: table: 252:0: dm_table_destroy: dm_put_device call missing for 1:0