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BUG: KASAN: slab-out-of-bounds in ecryptfs_verify_auth_tok_from_key+0x3b7/0x400 fs/ecryptfs/keystore.c:465
Read of size 2 at addr ffff888023d781d8 by task syz.1.584/7561

CPU: 1 UID: 0 PID: 7561 Comm: syz.1.584 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:
 <TASK>
 __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
 ecryptfs_verify_auth_tok_from_key+0x3b7/0x400 fs/ecryptfs/keystore.c:465
 ecryptfs_keyring_auth_tok_for_sig+0x9e/0x1f0 fs/ecryptfs/keystore.c:1606
 ecryptfs_init_global_auth_toks fs/ecryptfs/main.c:194 [inline]
 ecryptfs_validate_options fs/ecryptfs/main.c:420 [inline]
 ecryptfs_get_tree+0x57b/0x15b0 fs/ecryptfs/main.c:453
 vfs_get_tree+0x92/0x320 fs/super.c:1947
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3772 [inline]
 do_new_mount fs/namespace.c:3848 [inline]
 path_mount+0x7d0/0x24c0 fs/namespace.c:4168
 do_mount fs/namespace.c:4181 [inline]
 __do_sys_mount fs/namespace.c:4397 [inline]
 __se_sys_mount fs/namespace.c:4374 [inline]
 __ia32_sys_mount+0x292/0x310 fs/namespace.c:4374
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
 __do_fast_syscall_32+0x13a/0x8b0 arch/x86/entry/syscall_32.c:291
 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf709efec
Code: Unable to access opcode bytes at 0xf709efc2.
RSP: 002b:00000000f548d50c EFLAGS: 00000292 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 0000000080000400 RCX: 0000000080000000
RDX: 0000000080000480 RSI: 0000000000000000 RDI: 0000000080000500
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 7561:
 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:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5414 [inline]
 __kmalloc_noprof+0x32f/0x840 mm/slub.c:5439
 _kmalloc_noprof include/linux/slab.h:995 [inline]
 user_preparse+0x9b/0x1c0 security/keys/user_defined.c:67
 __key_create_or_update+0x463/0xe30 security/keys/key.c:857
 key_create_or_update+0x42/0x60 security/keys/key.c:1021
 __do_sys_add_key+0x2e8/0x460 security/keys/keyctl.c:134
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
 __do_fast_syscall_32+0x13a/0x8b0 arch/x86/entry/syscall_32.c:291
 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

The buggy address belongs to the object at ffff888023d781c0
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 24 bytes inside of
 allocated 25-byte region [ffff888023d781c0, ffff888023d781d9)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x23d78
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801c042780 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000400040 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 0x252800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_THISNODE), pid 5755, tgid 5755 (syz-executor), ts 175004965359
 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_pages_slowpath mm/page_alloc.c:4884 [inline]
 __alloc_frozen_pages_noprof+0x936/0x3300 mm/page_alloc.c:5449
 alloc_slab_page mm/slub.c:3347 [inline]
 allocate_slab mm/slub.c:3462 [inline]
 new_slab+0xa9/0x6e0 mm/slub.c:3513
 ___slab_alloc+0x5d1/0x810 mm/slub.c:4568
 slab_alloc_node mm/slub.c:4987 [inline]
 __do_kmalloc_node mm/slub.c:5413 [inline]
 __kmalloc_flags_noprof+0x470/0x8e0 mm/slub.c:5602
 _kmalloc_flags_noprof mm/slab.h:55 [inline]
 alloc_slab_obj_exts+0x6a/0x170 mm/slub.c:2186
 __memcg_slab_post_alloc_hook+0x40a/0x1270 mm/memcontrol.c:3649
 memcg_slab_post_alloc_hook mm/slub.c:2517 [inline]
 slab_post_alloc_hook mm/slub.c:4702 [inline]
 slab_alloc_node mm/slub.c:4996 [inline]
 kmem_cache_alloc_node_noprof+0x528/0x6e0 mm/slub.c:5068
 alloc_task_struct_node kernel/fork.c:188 [inline]
 dup_task_struct kernel/fork.c:922 [inline]
 copy_process+0x6a2/0x8370 kernel/fork.c:2133
 kernel_clone+0x176/0x9d0 kernel/fork.c:2766
 __do_compat_sys_ia32_clone+0xd4/0x120 arch/x86/kernel/sys_ia32.c:255
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
 __do_fast_syscall_32+0x13a/0x8b0 arch/x86/entry/syscall_32.c:291
 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
page last free pid 35 tgid 35 ts 165381584730 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
 __pagetable_free include/linux/mm.h:3804 [inline]
 pagetable_free include/linux/mm.h:3828 [inline]
 pagetable_dtor_free include/linux/mm.h:3927 [inline]
 __tlb_remove_table include/asm-generic/tlb.h:221 [inline]
 __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
 tlb_remove_table_rcu+0x2cf/0x380 mm/mmu_gather.c:291
 rcu_do_batch kernel/rcu/tree.c:2650 [inline]
 rcu_core+0x5f0/0x1260 kernel/rcu/tree.c:2919
 handle_softirqs+0x1e6/0x9d0 kernel/softirq.c:645
 run_ksoftirqd kernel/softirq.c:1099 [inline]
 run_ksoftirqd+0x38/0x60 kernel/softirq.c:1091
 smpboot_thread_fn+0x3d3/0xab0 kernel/smpboot.c:160
 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:
 ffff888023d78080: 00 00 00 00 fc fc fc fc fa fb fb fb fc fc fc fc
 ffff888023d78100: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
>ffff888023d78180: 00 00 00 00 fc fc fc fc 00 00 00 01 fc fc fc fc
                                                    ^
 ffff888023d78200: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff888023d78280: 00 00 00 00 fc fc fc fc 00 00 00 00 fc fc fc fc
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