================================================================== BUG: KASAN: slab-use-after-free in snapshot_ctr+0x1c20/0x1fd0 drivers/md/dm-snap.c:1282 Read of size 8 at addr ffff88802bca1b18 by task syz.3.76/6167 CPU: 0 UID: 0 PID: 6167 Comm: syz.3.76 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x13d/0x4b0 mm/kasan/report.c:482 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595 snapshot_ctr+0x1c20/0x1fd0 drivers/md/dm-snap.c:1282 dm_table_add_target+0x58b/0xee0 drivers/md/dm-table.c:749 populate_table drivers/md/dm-ioctl.c:1602 [inline] table_load+0x3b9/0x7b0 drivers/md/dm-ioctl.c:1645 ctl_ioctl+0x4d2/0xcc0 drivers/md/dm-ioctl.c:2221 dm_ctl_ioctl+0x22/0x30 drivers/md/dm-ioctl.c:2243 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6b2ad9f559 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:00007f6b2bc99028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f6b2b025fa0 RCX: 00007f6b2ad9f559 RDX: 00002000000006c0 RSI: 00000000c138fd09 RDI: 0000000000000007 RBP: 00007f6b2ae36b20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6b2b026038 R14: 00007f6b2b025fa0 R15: 00007ffe0b8870a8 Allocated by task 6167: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:409 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:426 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_node_noprof+0x30c/0x710 mm/slub.c:5582 _kmalloc_node_noprof include/linux/slab.h:1196 [inline] open_table_device drivers/md/dm.c:733 [inline] dm_get_table_device+0x2fc/0x820 drivers/md/dm.c:821 dm_get_device+0x525/0x7e0 drivers/md/dm-table.c:388 snapshot_ctr+0x201/0x1fd0 drivers/md/dm-snap.c:1267 dm_table_add_target+0x58b/0xee0 drivers/md/dm-table.c:749 populate_table drivers/md/dm-ioctl.c:1602 [inline] table_load+0x3b9/0x7b0 drivers/md/dm-ioctl.c:1645 ctl_ioctl+0x4d2/0xcc0 drivers/md/dm-ioctl.c:2221 dm_ctl_ioctl+0x22/0x30 drivers/md/dm-ioctl.c:2243 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6167: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:264 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:296 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2748 [inline] slab_free mm/slub.c:6509 [inline] kfree+0x22b/0x6d0 mm/slub.c:6802 close_table_device drivers/md/dm.c:798 [inline] dm_put_table_device+0x2bf/0x380 drivers/md/dm.c:841 upgrade_mode drivers/md/dm-table.c:326 [inline] dm_get_device+0x3f1/0x7e0 drivers/md/dm-table.c:399 snapshot_ctr+0x326/0x1fd0 drivers/md/dm-snap.c:1277 dm_table_add_target+0x58b/0xee0 drivers/md/dm-table.c:749 populate_table drivers/md/dm-ioctl.c:1602 [inline] table_load+0x3b9/0x7b0 drivers/md/dm-ioctl.c:1645 ctl_ioctl+0x4d2/0xcc0 drivers/md/dm-ioctl.c:2221 dm_ctl_ioctl+0x22/0x30 drivers/md/dm-ioctl.c:2243 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88802bca1b00 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 24 bytes inside of freed 96-byte region [ffff88802bca1b00, ffff88802bca1b60) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2bca1 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000000 ffff88801d042280 dead000000000100 dead000000000122 raw: 0000000000000000 0000000000200020 00000000f5000000 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 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 7012065045 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871 prep_new_page mm/page_alloc.c:1879 [inline] get_page_from_freelist+0x110d/0x35d0 mm/page_alloc.c:3943 __alloc_frozen_pages_noprof+0x2e9/0x32e0 mm/page_alloc.c:5436 alloc_slab_page mm/slub.c:3347 [inline] allocate_slab mm/slub.c:3462 [inline] new_slab+0xa9/0x6e0 mm/slub.c:3513 refill_objects+0xe3/0x410 mm/slub.c:7418 refill_sheaf mm/slub.c:2885 [inline] __pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774 alloc_from_pcs mm/slub.c:4850 [inline] slab_alloc_node mm/slub.c:4984 [inline] __kmalloc_cache_node_noprof+0x517/0x710 mm/slub.c:5578 _kmalloc_node_noprof include/linux/slab.h:1196 [inline] __get_vm_area_node+0x124/0x350 mm/vmalloc.c:3237 __vmalloc_node_range_noprof+0x268/0x1420 mm/vmalloc.c:4064 __vmalloc_node_noprof+0xad/0xf0 mm/vmalloc.c:4165 pptp_init_module+0x25/0x120 drivers/net/ppp/pptp.c:652 do_one_initcall+0x11c/0x6f0 init/main.c:1362 do_initcall_level init/main.c:1424 [inline] do_initcalls init/main.c:1440 [inline] do_basic_setup init/main.c:1460 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1675 kernel_init+0x21/0x1e0 init/main.c:1565 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 page last free pid 36 tgid 36 ts 7011238512 stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] __free_pages_prepare mm/page_alloc.c:1418 [inline] __free_frozen_pages+0x79f/0x10f0 mm/page_alloc.c:2962 __kasan_populate_vmalloc_do mm/kasan/shadow.c:393 [inline] __kasan_populate_vmalloc+0x1ea/0x210 mm/kasan/shadow.c:424 kasan_populate_vmalloc include/linux/kasan.h:580 [inline] alloc_vmap_area+0x963/0x2bc0 mm/vmalloc.c:2145 __get_vm_area_node+0x1ed/0x350 mm/vmalloc.c:3248 __vmalloc_node_range_noprof+0x268/0x1420 mm/vmalloc.c:4064 __vmalloc_node_noprof+0xad/0xf0 mm/vmalloc.c:4165 alloc_thread_stack_node kernel/fork.c:359 [inline] dup_task_struct kernel/fork.c:930 [inline] copy_process+0x80b/0x84c0 kernel/fork.c:2143 kernel_clone+0x176/0x9d0 kernel/fork.c:2785 user_mode_thread+0xd1/0x120 kernel/fork.c:2862 call_usermodehelper_exec_work kernel/umh.c:169 [inline] call_usermodehelper_exec_work+0xcb/0x180 kernel/umh.c:155 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Memory state around the buggy address: ffff88802bca1a00: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc ffff88802bca1a80: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc >ffff88802bca1b00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff88802bca1b80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88802bca1c00: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc ==================================================================