================================================================== BUG: KASAN: use-after-free in do_new_mount_fc fs/namespace.c:2773 [inline] BUG: KASAN: use-after-free in do_new_mount fs/namespace.c:2825 [inline] BUG: KASAN: use-after-free in do_mount+0x1b5f/0x1d10 fs/namespace.c:3143 Read of size 8 at addr ffff8880960dd268 by task syz-executor.5/5611 CPU: 0 PID: 5611 Comm: syz-executor.5 Not tainted 5.4.0-rc1-next-20191003 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:634 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 do_new_mount_fc fs/namespace.c:2773 [inline] do_new_mount fs/namespace.c:2825 [inline] do_mount+0x1b5f/0x1d10 fs/namespace.c:3143 ksys_mount+0xdb/0x150 fs/namespace.c:3352 __do_sys_mount fs/namespace.c:3366 [inline] __se_sys_mount fs/namespace.c:3363 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3363 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459a29 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fe23b532c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459a29 RDX: 0000000020000a40 RSI: 00000000200005c0 RDI: 0000000000000000 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe23b5336d4 R13: 00000000004c6224 R14: 00000000004db278 R15: 00000000ffffffff Allocated by task 5611: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc mm/kasan/common.c:510 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:518 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc mm/slab.c:3319 [inline] kmem_cache_alloc+0x121/0x710 mm/slab.c:3483 kmem_cache_zalloc include/linux/slab.h:680 [inline] alloc_vfsmnt+0x28/0x680 fs/namespace.c:177 vfs_create_mount+0x96/0x500 fs/namespace.c:940 do_new_mount_fc fs/namespace.c:2763 [inline] do_new_mount fs/namespace.c:2825 [inline] do_mount+0x17ae/0x1d10 fs/namespace.c:3143 ksys_mount+0xdb/0x150 fs/namespace.c:3352 __do_sys_mount fs/namespace.c:3366 [inline] __se_sys_mount fs/namespace.c:3363 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3363 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] kasan_set_free_info mm/kasan/common.c:332 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480 __cache_free mm/slab.c:3425 [inline] kmem_cache_free+0x86/0x320 mm/slab.c:3693 free_vfsmnt+0x6f/0x90 fs/namespace.c:554 delayed_free_vfsmnt+0x16/0x20 fs/namespace.c:559 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch kernel/rcu/tree.c:2157 [inline] rcu_core+0x581/0x1560 kernel/rcu/tree.c:2377 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2386 __do_softirq+0x262/0x98c kernel/softirq.c:292 The buggy address belongs to the object at ffff8880960dd240 which belongs to the cache mnt_cache of size 312 The buggy address is located 40 bytes inside of 312-byte region [ffff8880960dd240, ffff8880960dd378) The buggy address belongs to the page: page:ffffea0002583740 refcount:1 mapcount:0 mapping:ffff8880aa5a88c0 index:0x0 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea0002638f08 ffffea000256ab48 ffff8880aa5a88c0 raw: 0000000000000000 ffff8880960dd0c0 000000010000000a 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880960dd100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880960dd180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc >ffff8880960dd200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff8880960dd280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880960dd300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc ==================================================================