================================================================== BUG: KASAN: slab-use-after-free in snapshot_ctr+0x586/0x1350 drivers/md/dm-snap.c:1288 Read of size 8 at addr ffff8881142d1c98 by task syz.1.18/416 CPU: 1 UID: 0 PID: 416 Comm: syz.1.18 Not tainted syzkaller #0 ff996278633adec6fd25d1632b496761701c4fe9 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026 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+0x59f/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+0x123/0x1b0 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: 0033:0x7f722b99fb19 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:00007f722c7ac028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f722bc25fa0 RCX: 00007f722b99fb19 RDX: 0000200000000440 RSI: 00000000c138fd09 RDI: 0000000000000003 RBP: 00007f722ba37b70 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f722bc26038 R14: 00007f722bc25fa0 R15: 00007fff08bdb2b8 Allocated by task 416: 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+0x59f/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+0x123/0x1b0 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 416: 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+0x59f/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+0x123/0x1b0 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 ffff8881142d1c80 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 24 bytes inside of freed 96-byte region [ffff8881142d1c80, ffff8881142d1ce0) The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1142d1 flags: 0x4000000000000000(zone=1) page_type: f5(slab) raw: 4000000000000000 ffff888100041280 dead000000000122 0000000000000000 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 0x152cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 323, tgid 323 (udevd), ts 24455355004, free_ts 24454599864 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] __do_kmalloc_node mm/slub.c:4396 [inline] __kmalloc_node_noprof+0x2e7/0x500 mm/slub.c:4403 __kvmalloc_node_noprof+0x128/0x300 mm/util.c:672 simple_xattr_alloc+0x67/0x140 fs/xattr.c:1093 shmem_initxattrs+0x24f/0x530 mm/shmem.c:4082 security_inode_init_security+0x431/0x600 security/security.c:1853 shmem_mknod+0xd5/0x200 mm/shmem.c:3689 shmem_create+0x38/0x50 mm/shmem.c:3753 lookup_open fs/namei.c:3603 [inline] open_last_lookups fs/namei.c:3702 [inline] path_openat+0x150b/0x35a0 fs/namei.c:3938 do_filp_open+0x1f2/0x440 fs/namei.c:3968 page last free pid 323 tgid 323 stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1391 [inline] free_unref_page+0xb99/0xf50 mm/page_alloc.c:2877 __free_pages+0x6b/0x3b0 mm/page_alloc.c:5403 __free_slab+0xb2/0x110 mm/slub.c:2758 free_slab+0x18/0xe0 mm/slub.c:2781 discard_slab+0x23/0x40 mm/slub.c:2787 __slab_free+0x1fd/0x2a0 mm/slub.c:4627 do_slab_free mm/slub.c:4668 [inline] ___cache_free+0xc9/0xe0 mm/slub.c:4783 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0xb5/0x130 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x14f/0x180 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x28/0x90 mm/kasan/common.c:331 kasan_slab_alloc include/linux/kasan.h:251 [inline] slab_post_alloc_hook mm/slub.c:4204 [inline] slab_alloc_node mm/slub.c:4253 [inline] kmem_cache_alloc_noprof+0x1bf/0x410 mm/slub.c:4262 prepare_creds+0x47/0x6b0 kernel/cred.c:215 selinux_lsm_setattr+0x216/0x8e0 security/selinux/hooks.c:6498 selinux_setprocattr+0x53/0x70 security/selinux/hooks.c:6623 security_setprocattr+0x35b/0x380 security/security.c:4265 proc_pid_attr_write+0x2aa/0x310 fs/proc/base.c:2865 Memory state around the buggy address: ffff8881142d1b80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff8881142d1c00: 00 00 00 00 00 00 00 00 03 fc fc fc fc fc fc fc >ffff8881142d1c80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff8881142d1d00: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc ffff8881142d1d80: 00 00 00 00 00 00 00 00 03 fc fc fc fc fc fc fc ================================================================== device-mapper: table: 252:0: device 1:2 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 1:2 device-mapper: ioctl: The device has no table. device-mapper: table: 252:0: device 1:2 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 1:2