================================================================== BUG: KASAN: slab-use-after-free in scr_memcpyw include/linux/vt_buffer.h:38 [inline] BUG: KASAN: slab-use-after-free in fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:623 Read of size 256 at addr ffff8880533c63c0 by task syz.1.1935/16765 CPU: 0 UID: 0 PID: 16765 Comm: syz.1.1935 Tainted: G U syzkaller #0 PREEMPT(full) Tainted: [U]=USER Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xcd/0x630 mm/kasan/report.c:482 kasan_report+0xe0/0x110 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:194 [inline] kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:200 __asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105 scr_memcpyw include/linux/vt_buffer.h:38 [inline] fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:623 fbcon_init+0xd77/0x1900 drivers/video/fbdev/core/fbcon.c:1156 visual_init+0x320/0x620 drivers/tty/vt/vt.c:1020 do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3960 vt_bind drivers/tty/vt/vt.c:4116 [inline] store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4188 dev_attr_store+0x58/0x80 drivers/base/core.c:2437 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 kernfs_fop_write_iter+0x3af/0x570 fs/kernfs/file.c:352 iter_file_splice_write+0xa21/0x12e0 fs/splice.c:738 do_splice_from fs/splice.c:938 [inline] direct_splice_actor+0x18f/0x6c0 fs/splice.c:1161 splice_direct_to_actor+0x342/0xa30 fs/splice.c:1105 do_splice_direct_actor fs/splice.c:1204 [inline] do_splice_direct+0x174/0x240 fs/splice.c:1230 do_sendfile+0xb06/0xe50 fs/read_write.c:1370 __do_sys_sendfile64 fs/read_write.c:1431 [inline] __se_sys_sendfile64 fs/read_write.c:1417 [inline] __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1417 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6ed338eec9 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:00007f6ed415d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f6ed35e5fa0 RCX: 00007f6ed338eec9 RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000001 RBP: 00007f6ed3411f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6ed35e6038 R14: 00007f6ed35e5fa0 R15: 00007ffc1fb9e238 Allocated by task 16651: kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 kasan_save_track+0x14/0x30 mm/kasan/common.c:77 unpoison_slab_object mm/kasan/common.c:342 [inline] __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:368 kasan_slab_alloc include/linux/kasan.h:252 [inline] slab_post_alloc_hook mm/slub.c:4946 [inline] slab_alloc_node mm/slub.c:5245 [inline] kmem_cache_alloc_node_noprof+0x28a/0x770 mm/slub.c:5297 kmalloc_reserve+0x18b/0x2c0 net/core/skbuff.c:579 __alloc_skb+0x166/0x380 net/core/skbuff.c:670 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_skb_with_frags+0xe0/0x860 net/core/skbuff.c:6671 sock_alloc_send_pskb+0x7f9/0x980 net/core/sock.c:2965 sock_alloc_send_skb include/net/sock.h:1859 [inline] __ip_append_data+0x2149/0x41a0 net/ipv4/ip_output.c:1127 ip_make_skb+0x27f/0x300 net/ipv4/ip_output.c:1574 udp_sendmsg+0x17d7/0x2870 net/ipv4/udp.c:1479 inet_sendmsg+0x105/0x140 net/ipv4/af_inet.c:853 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x973/0xc70 net/socket.c:2630 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684 __sys_sendmmsg+0x200/0x420 net/socket.c:2773 __do_sys_sendmmsg net/socket.c:2800 [inline] __se_sys_sendmmsg net/socket.c:2797 [inline] __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2797 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 16651: kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 kasan_save_track+0x14/0x30 mm/kasan/common.c:77 __kasan_save_free_info+0x3b/0x60 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+0x5f/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] kmem_cache_free+0x2d4/0x6c0 mm/slub.c:6676 skb_kfree_head net/core/skbuff.c:1046 [inline] skb_kfree_head net/core/skbuff.c:1043 [inline] skb_free_head+0x1b7/0x210 net/core/skbuff.c:1060 skb_release_data+0x795/0x9e0 net/core/skbuff.c:1087 skb_release_all net/core/skbuff.c:1152 [inline] kfree_skb_add_bulk net/core/skbuff.c:1225 [inline] kfree_skb_list_reason+0x2c4/0x4c0 net/core/skbuff.c:1247 __dev_xmit_skb net/core/dev.c:4227 [inline] __dev_queue_xmit+0x2bfa/0x4490 net/core/dev.c:4729 dev_queue_xmit include/linux/netdevice.h:3365 [inline] neigh_hh_output include/net/neighbour.h:531 [inline] neigh_output include/net/neighbour.h:545 [inline] ip_finish_output2+0xc38/0x21a0 net/ipv4/ip_output.c:237 __ip_finish_output.part.0+0x1b4/0x350 net/ipv4/ip_output.c:315 __ip_finish_output net/ipv4/ip_output.c:303 [inline] ip_finish_output net/ipv4/ip_output.c:325 [inline] NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x35f/0xa90 net/ipv4/ip_output.c:438 dst_output include/net/dst.h:464 [inline] ip_local_out net/ipv4/ip_output.c:131 [inline] ip_send_skb+0x437/0x590 net/ipv4/ip_output.c:1508 udp_send_skb+0x71d/0x15b0 net/ipv4/udp.c:1195 udp_sendmsg+0x1813/0x2870 net/ipv4/udp.c:1484 inet_sendmsg+0x105/0x140 net/ipv4/af_inet.c:853 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x973/0xc70 net/socket.c:2630 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684 __sys_sendmmsg+0x200/0x420 net/socket.c:2773 __do_sys_sendmmsg net/socket.c:2800 [inline] __se_sys_sendmmsg net/socket.c:2797 [inline] __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2797 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff8880533c63c0 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 0 bytes inside of freed 704-byte region [ffff8880533c63c0, ffff8880533c6680) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x533c4 head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801e6d3c80 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000130013 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801e6d3c80 0000000000000000 dead000000000001 head: 0000000000000000 0000000000130013 00000000f5000000 0000000000000000 head: 00fff00000000002 ffffea00014cf101 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 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 15939, tgid 15931 (syz.2.1785), ts 621313255038, free_ts 604464487732 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1850 prep_new_page mm/page_alloc.c:1858 [inline] get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3884 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5183 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:3030 [inline] allocate_slab mm/slub.c:3203 [inline] new_slab+0x24a/0x360 mm/slub.c:3257 ___slab_alloc+0xdc4/0x1ae0 mm/slub.c:4627 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4746 __slab_alloc_node mm/slub.c:4822 [inline] slab_alloc_node mm/slub.c:5233 [inline] kmem_cache_alloc_node_noprof+0x43c/0x770 mm/slub.c:5297 kmalloc_reserve+0x18b/0x2c0 net/core/skbuff.c:579 __alloc_skb+0x166/0x380 net/core/skbuff.c:670 alloc_skb include/linux/skbuff.h:1383 [inline] __tcp_send_ack.part.0+0x66/0x6f0 net/ipv4/tcp_output.c:4418 __tcp_send_ack net/ipv4/tcp_output.c:4451 [inline] tcp_send_ack+0x84/0xa0 net/ipv4/tcp_output.c:4451 __tcp_ack_snd_check+0x188/0xad0 net/ipv4/tcp_input.c:5907 tcp_ack_snd_check net/ipv4/tcp_input.c:5953 [inline] tcp_ack_snd_check net/ipv4/tcp_input.c:5947 [inline] tcp_rcv_established+0xb94/0x3700 net/ipv4/tcp_input.c:6444 tcp_v4_do_rcv+0x5ca/0xa90 net/ipv4/tcp_ipv4.c:1931 tcp_v4_rcv+0x3077/0x47d0 net/ipv4/tcp_ipv4.c:2374 page last free pid 15581 tgid 15580 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1394 [inline] __free_frozen_pages+0x7df/0x1160 mm/page_alloc.c:2906 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:352 kasan_slab_alloc include/linux/kasan.h:252 [inline] slab_post_alloc_hook mm/slub.c:4946 [inline] slab_alloc_node mm/slub.c:5245 [inline] __do_kmalloc_node mm/slub.c:5602 [inline] __kmalloc_noprof+0x2e8/0x880 mm/slub.c:5615 kmalloc_noprof include/linux/slab.h:961 [inline] tomoyo_realpath_from_path+0xc2/0x6e0 security/tomoyo/realpath.c:251 tomoyo_get_exe+0x63/0xa0 security/tomoyo/util.c:978 tomoyo_manager security/tomoyo/common.c:943 [inline] tomoyo_write_control+0x689/0x1430 security/tomoyo/common.c:2823 vfs_write+0x2a0/0x11d0 fs/read_write.c:684 ksys_write+0x12a/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff8880533c6280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880533c6300: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff8880533c6380: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ^ ffff8880533c6400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880533c6480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================