================================================================== BUG: KASAN: slab-use-after-free in snapshot_ctr+0x586/0x1350 drivers/md/dm-snap.c:1288 Read of size 8 at addr ffff888139a81218 by task syz.4.310/1687 CPU: 0 UID: 0 PID: 1687 Comm: syz.4.310 Not tainted syzkaller #0 b337f5a91fe3fd607f319abe4015f181b3f4c6c0 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+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+0x8f0/0xde0 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: 0033:0x7fc6eb99f559 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:00007fc6ec86a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fc6ebc25fa0 RCX: 00007fc6eb99f559 RDX: 00002000000004c0 RSI: 00000000c138fd09 RDI: 0000000000000004 RBP: 00007fc6eba36b20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc6ebc26038 R14: 00007fc6ebc25fa0 R15: 00007ffc2d575128 Allocated by task 1687: 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+0x8f0/0xde0 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 1687: 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+0x8f0/0xde0 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 ffff888139a81200 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 24 bytes inside of freed 96-byte region [ffff888139a81200, ffff888139a81260) The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x139a81 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 1686, tgid 1686 (syz.4.310), ts 77565338429, free_ts 77544098363 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_node_noprof+0x2ae/0x430 mm/slub.c:4436 kmalloc_node_noprof include/linux/slab.h:1004 [inline] __get_vm_area_node+0x150/0x390 mm/vmalloc.c:3148 __vmalloc_node_range_noprof+0x340/0x1300 mm/vmalloc.c:3838 alloc_thread_stack_node kernel/fork.c:325 [inline] dup_task_struct+0x5d6/0xd80 kernel/fork.c:1124 copy_process+0x579/0x3370 kernel/fork.c:2249 kernel_clone+0x233/0x810 kernel/fork.c:2852 __do_sys_clone3 kernel/fork.c:3158 [inline] __se_sys_clone3+0x33e/0x360 kernel/fork.c:3137 __x64_sys_clone3+0x5f/0x80 kernel/fork.c:3137 x64_sys_call+0x28fc/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:436 page last free pid 33 tgid 33 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 pagetable_free include/linux/mm.h:3091 [inline] pagetable_dtor_free include/linux/mm.h:3181 [inline] __tlb_remove_table include/asm-generic/tlb.h:217 [inline] __tlb_remove_table_free mm/mmu_gather.c:228 [inline] tlb_remove_table_rcu+0x2b2/0x3d0 mm/mmu_gather.c:283 rcu_do_batch+0x56d/0xcb0 kernel/rcu/tree.c:2575 nocb_cb_wait kernel/rcu/tree_nocb.h:923 [inline] rcu_nocb_cb_kthread+0x533/0xb60 kernel/rcu/tree_nocb.h:957 kthread+0x2c4/0x360 kernel/kthread.c:389 ret_from_fork+0x64/0xa0 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Memory state around the buggy address: ffff888139a81100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888139a81180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888139a81200: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff888139a81280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888139a81300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== device-mapper: table: 252:2: device 1:9 not in table devices list device-mapper: table: 252:2: snapshot: COW device cannot be the same as origin device (-EINVAL) device-mapper: ioctl: error adding target to table device-mapper: table: 252:2: dm_table_destroy: dm_put_device call missing for 1:9