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BUG: KASAN: slab-out-of-bounds in vc_con_write_normal drivers/tty/vt/vt.c:3238 [inline]
BUG: KASAN: slab-out-of-bounds in do_con_write+0x394b/0x4a30 drivers/tty/vt/vt.c:3329
Write of size 2 at addr ffff8880449e3f60 by task syz.3.2481/17749

CPU: 0 UID: 0 PID: 17749 Comm: syz.3.2481 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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
 vc_con_write_normal drivers/tty/vt/vt.c:3238 [inline]
 do_con_write+0x394b/0x4a30 drivers/tty/vt/vt.c:3329
 con_write+0x23/0xb0 drivers/tty/vt/vt.c:3661
 process_output_block drivers/tty/n_tty.c:557 [inline]
 n_tty_write+0x431/0x1160 drivers/tty/n_tty.c:2366
 iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
 file_tty_write.isra.0+0x4d2/0x890 drivers/tty/tty_io.c:1081
 tty_write drivers/tty/tty_io.c:1102 [inline]
 redirected_tty_write drivers/tty/tty_io.c:1125 [inline]
 redirected_tty_write+0xd4/0x120 drivers/tty/tty_io.c:1105
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f25fd99de99
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:00007f25fe7aa028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f25fdc26180 RCX: 00007f25fd99de99
RDX: 0000000000000006 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007f25fda33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f25fdc26218 R14: 00007f25fdc26180 R15: 00007ffe7b325e18
 </TASK>

Allocated by task 5642:
 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:5362 [inline]
 __kmalloc_noprof+0x322/0x820 mm/slub.c:5387
 _kmalloc_noprof include/linux/slab.h:973 [inline]
 tomoyo_realpath_from_path+0xb6/0x690 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x276/0x460 security/tomoyo/file.c:827
 security_inode_getattr+0x116/0x280 security/security.c:1895
 vfs_getattr fs/stat.c:259 [inline]
 vfs_statx_path fs/stat.c:299 [inline]
 vfs_statx+0x11f/0x3f0 fs/stat.c:356
 vfs_fstatat+0x77/0xe0 fs/stat.c:373
 __do_sys_newfstatat+0x9d/0x120 fs/stat.c:538
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5642:
 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:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2705 [inline]
 slab_free mm/slub.c:6405 [inline]
 kfree+0x22b/0x6c0 mm/slub.c:6720
 tomoyo_realpath_from_path+0x19c/0x690 security/tomoyo/realpath.c:286
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x276/0x460 security/tomoyo/file.c:827
 security_inode_getattr+0x116/0x280 security/security.c:1895
 vfs_getattr fs/stat.c:259 [inline]
 vfs_statx_path fs/stat.c:299 [inline]
 vfs_statx+0x11f/0x3f0 fs/stat.c:356
 vfs_fstatat+0x77/0xe0 fs/stat.c:373
 __do_sys_newfstatat+0x9d/0x120 fs/stat.c:538
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880449e2000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 3936 bytes to the right of
 allocated 4096-byte region [ffff8880449e2000, ffff8880449e3000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x449e0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813fe24140 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fe24140 dead000000000100 dead000000000122
head: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 11820, tgid 11819 (syz.3.1271), ts 468679535282, free_ts 464472117058
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3294 [inline]
 allocate_slab mm/slub.c:3408 [inline]
 new_slab+0xa2/0x650 mm/slub.c:3454
 refill_objects+0xe3/0x410 mm/slub.c:7338
 refill_sheaf mm/slub.c:2832 [inline]
 __pcs_replace_empty_main+0x376/0x680 mm/slub.c:4703
 alloc_from_pcs mm/slub.c:4801 [inline]
 slab_alloc_node mm/slub.c:4933 [inline]
 __do_kmalloc_node mm/slub.c:5361 [inline]
 __kmalloc_noprof+0x66d/0x820 mm/slub.c:5387
 _kmalloc_noprof include/linux/slab.h:973 [inline]
 _kzalloc_noprof include/linux/slab.h:1290 [inline]
 ops_init+0x77/0x5f0 net/core/net_namespace.c:127
 setup_net+0x118/0x3a0 net/core/net_namespace.c:446
 copy_net_ns+0x46f/0x7c0 net/core/net_namespace.c:579
 create_new_namespaces+0x3ea/0xac0 kernel/nsproxy.c:132
 unshare_nsproxy_namespaces+0xf2/0x220 kernel/nsproxy.c:234
 ksys_unshare+0x438/0xab0 kernel/fork.c:3269
 __do_sys_unshare kernel/fork.c:3343 [inline]
 __se_sys_unshare kernel/fork.c:3341 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:3341
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 11703 tgid 11691 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
 __folio_put+0x3b4/0x5f0 mm/swap.c:112
 folio_put include/linux/mm.h:2124 [inline]
 put_page include/linux/mm.h:2193 [inline]
 put_netmem include/net/netmem.h:394 [inline]
 skb_page_unref include/linux/skbuff_ref.h:43 [inline]
 __skb_frag_unref include/linux/skbuff_ref.h:56 [inline]
 skb_release_data+0x649/0x8e0 net/core/skbuff.c:1110
 skb_release_all net/core/skbuff.c:1191 [inline]
 __kfree_skb net/core/skbuff.c:1205 [inline]
 sk_skb_reason_drop+0x102/0x1b0 net/core/skbuff.c:1244
 kfree_skb_reason include/linux/skbuff.h:1323 [inline]
 __skb_queue_purge_reason include/linux/skbuff.h:3441 [inline]
 __skb_queue_purge include/linux/skbuff.h:3446 [inline]
 mptcp_destroy_common+0x2d8/0x430 net/mptcp/protocol.c:3432
 mptcp_destroy+0x9b/0x120 net/mptcp/protocol.c:3639
 __mptcp_destroy_sock+0x1ad/0x3f0 net/mptcp/protocol.c:3272
 __mptcp_close+0x747/0xc70 net/mptcp/protocol.c:3374
 mptcp_close+0x28/0xe0 net/mptcp/protocol.c:3389
 inet_release+0xed/0x200 net/ipv4/af_inet.c:442
 __sock_release+0xb3/0x260 net/socket.c:710
 sock_close+0x1c/0x30 net/socket.c:1501
 __fput+0x3ff/0xb50 fs/file_table.c:512
 task_work_run+0x150/0x240 kernel/task_work.c:233
 get_signal+0x1bd/0x21e0 kernel/signal.c:2818
 arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880449e3e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880449e3e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880449e3f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                       ^
 ffff8880449e3f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880449e4000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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