================================================================== BUG: KASAN: slab-use-after-free in afs_dynroot_readdir_cells fs/afs/dynroot.c:296 [inline] BUG: KASAN: slab-use-after-free in afs_dynroot_readdir+0x844/0x9a0 fs/afs/dynroot.c:352 Read of size 4 at addr ffff888051e63948 by task syz.0.0/5330 CPU: 0 UID: 0 PID: 5330 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 afs_dynroot_readdir_cells fs/afs/dynroot.c:296 [inline] afs_dynroot_readdir+0x844/0x9a0 fs/afs/dynroot.c:352 iterate_dir+0x396/0x570 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64+0xe4/0x260 fs/readdir.c:396 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f996738eec9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f99682c6038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 00007f99675e5fa0 RCX: 00007f996738eec9 RDX: 0000000000000046 RSI: 00002000000000c0 RDI: 0000000000000005 RBP: 00007f9967411f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f99675e6038 R14: 00007f99675e5fa0 R15: 00007ffe6d21d708 Allocated by task 5330: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 poison_kmalloc_redzone mm/kasan/common.c:400 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:417 kasan_kmalloc include/linux/kasan.h:262 [inline] __kmalloc_cache_noprof+0x3d5/0x6f0 mm/slub.c:5724 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] afs_alloc_cell fs/afs/cell.c:137 [inline] afs_lookup_cell+0x4db/0x1860 fs/afs/cell.c:265 afs_dynroot_lookup_cell fs/afs/dynroot.c:111 [inline] afs_dynroot_lookup+0x27a/0x8c0 fs/afs/dynroot.c:159 __lookup_slow+0x297/0x3d0 fs/namei.c:1816 lookup_slow+0x53/0x70 fs/namei.c:1833 walk_component+0x2d2/0x400 fs/namei.c:2151 lookup_last fs/namei.c:2652 [inline] path_lookupat+0x163/0x430 fs/namei.c:2676 filename_lookup+0x212/0x570 fs/namei.c:2705 user_path_at+0x3a/0x60 fs/namei.c:3215 do_mount fs/namespace.c:4047 [inline] __do_sys_mount fs/namespace.c:4238 [inline] __se_sys_mount+0x2d4/0x410 fs/namespace.c:4215 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 5330: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587 kasan_save_free_info mm/kasan/kasan.h:406 [inline] poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2514 [inline] slab_free mm/slub.c:6566 [inline] kfree+0x19a/0x6d0 mm/slub.c:6773 afs_cell_destroy+0x1a0/0x2c0 fs/afs/cell.c:525 rcu_do_batch kernel/rcu/tree.c:2605 [inline] rcu_core+0xcab/0x1770 kernel/rcu/tree.c:2861 handle_softirqs+0x283/0x870 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:723 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 Last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559 __call_rcu_common kernel/rcu/tree.c:3123 [inline] call_rcu+0x157/0x9c0 kernel/rcu/tree.c:3243 process_one_work kernel/workqueue.c:3263 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3346 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Second to last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559 insert_work+0x3d/0x330 kernel/workqueue.c:2186 __queue_work+0xcd2/0xfb0 kernel/workqueue.c:2341 queue_work_on+0x181/0x270 kernel/workqueue.c:2392 queue_work include/linux/workqueue.h:669 [inline] afs_put_cell+0x142/0x240 fs/afs/cell.c:570 afs_manage_cell_work+0xbe2/0x1650 fs/afs/cell.c:860 process_one_work kernel/workqueue.c:3263 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3346 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 The buggy address belongs to the object at ffff888051e63800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 328 bytes inside of freed 1024-byte region [ffff888051e63800, ffff888051e63c00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x51e60 head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 04fff00000000040 ffff88801a041dc0 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000 head: 04fff00000000040 ffff88801a041dc0 dead000000000122 0000000000000000 head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000 head: 04fff00000000002 ffffea0001479801 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 3106, tgid 3106 (kworker/u4:11), ts 69730008116, free_ts 0 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850 prep_new_page mm/page_alloc.c:1858 [inline] get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3884 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:3030 [inline] allocate_slab+0x96/0x3a0 mm/slub.c:3203 new_slab mm/slub.c:3257 [inline] ___slab_alloc+0xe94/0x1920 mm/slub.c:4627 __slab_alloc+0x65/0x100 mm/slub.c:4746 __slab_alloc_node mm/slub.c:4822 [inline] slab_alloc_node mm/slub.c:5233 [inline] __do_kmalloc_node mm/slub.c:5602 [inline] __kmalloc_noprof+0x471/0x7f0 mm/slub.c:5615 kmalloc_noprof include/linux/slab.h:961 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] neigh_alloc net/core/neighbour.c:522 [inline] ___neigh_create+0x6d5/0x2260 net/core/neighbour.c:656 ip6_finish_output2+0x1175/0x1480 net/ipv6/ip6_output.c:128 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline] ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:220 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247 NF_HOOK include/linux/netfilter.h:318 [inline] ndisc_send_skb+0xbce/0x1510 net/ipv6/ndisc.c:512 addrconf_dad_completed+0x7ae/0xd60 net/ipv6/addrconf.c:4360 addrconf_dad_work+0xc36/0x14b0 net/ipv6/addrconf.c:-1 process_one_work kernel/workqueue.c:3263 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3346 page_owner free stack trace missing Memory state around the buggy address: ffff888051e63800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888051e63880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888051e63900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888051e63980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888051e63a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================