================================================================== BUG: KASAN: slab-use-after-free in scr_memcpyw include/linux/vt_buffer.h:49 [inline] BUG: KASAN: slab-use-after-free in fbcon_prepare_logo+0x4e2/0xa70 drivers/video/fbdev/core/fbcon.c:602 Read of size 256 at addr ffff888061fd8760 by task syz.0.2400/14086 CPU: 0 PID: 14086 Comm: syz.0.2400 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0xa8/0x210 mm/kasan/report.c:468 kasan_report+0x117/0x150 mm/kasan/report.c:581 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x241/0x290 mm/kasan/generic.c:187 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105 scr_memcpyw include/linux/vt_buffer.h:49 [inline] fbcon_prepare_logo+0x4e2/0xa70 drivers/video/fbdev/core/fbcon.c:602 fbcon_init+0x1380/0x2460 drivers/video/fbdev/core/fbcon.c:1137 visual_init+0x2dd/0x650 drivers/tty/vt/vt.c:1023 do_bind_con_driver+0x859/0x1030 drivers/tty/vt/vt.c:3645 vt_bind drivers/tty/vt/vt.c:3801 [inline] store_bind+0x798/0xa20 drivers/tty/vt/vt.c:3873 kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352 call_write_iter include/linux/fs.h:2018 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x474/0x9a0 fs/read_write.c:584 ksys_write+0x151/0x260 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f69e219e019 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:00007f69e30ec028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f69e2426090 RCX: 00007f69e219e019 RDX: 0000000000000001 RSI: 0000200000000280 RDI: 0000000000000003 RBP: 00007f69e223500c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f69e2426128 R14: 00007f69e2426090 R15: 00007ffe4e18bba8 Allocated by task 14064: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329 kasan_slab_alloc include/linux/kasan.h:188 [inline] slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770 slab_alloc_node mm/slub.c:3495 [inline] kmem_cache_alloc_node+0x1af/0x310 mm/slub.c:3540 kmalloc_reserve+0x95/0x240 net/core/skbuff.c:562 __alloc_skb+0x138/0x2c0 net/core/skbuff.c:653 skb_copy+0x126/0x700 net/core/skbuff.c:1984 mac80211_hwsim_tx_frame_no_nl+0xcb2/0x11e0 drivers/net/wireless/virtual/mac80211_hwsim.c:1840 mac80211_hwsim_tx_frame+0x1b5/0x200 drivers/net/wireless/virtual/mac80211_hwsim.c:2176 mac80211_hwsim_beacon_tx+0x3df/0x770 drivers/net/wireless/virtual/mac80211_hwsim.c:2269 __iterate_interfaces+0x225/0x4c0 net/mac80211/util.c:766 ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:802 mac80211_hwsim_beacon+0xbb/0x1b0 drivers/net/wireless/virtual/mac80211_hwsim.c:2295 __run_hrtimer kernel/time/hrtimer.c:1754 [inline] __hrtimer_run_queues+0x525/0xc10 kernel/time/hrtimer.c:1818 hrtimer_run_softirq+0x177/0x290 kernel/time/hrtimer.c:1835 handle_softirqs+0x27d/0x820 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 Freed by task 1096: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237 kasan_slab_free include/linux/kasan.h:164 [inline] slab_free_hook mm/slub.c:1811 [inline] slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837 slab_free mm/slub.c:3830 [inline] __kmem_cache_free+0xba/0x1f0 mm/slub.c:3843 skb_kfree_head net/core/skbuff.c:946 [inline] skb_free_head net/core/skbuff.c:958 [inline] skb_release_data+0x609/0x7f0 net/core/skbuff.c:988 skb_release_all net/core/skbuff.c:1054 [inline] __kfree_skb net/core/skbuff.c:1068 [inline] kfree_skb_reason+0x10e/0x170 net/core/skbuff.c:1104 kfree_skb include/linux/skbuff.h:1264 [inline] ieee80211_iface_work+0x7a0/0xc90 net/mac80211/iface.c:1711 cfg80211_wiphy_work+0x228/0x260 net/wireless/core.c:437 process_one_work kernel/workqueue.c:2653 [inline] process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2730 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2811 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 The buggy address belongs to the object at ffff888061fd8680 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 224 bytes inside of freed 704-byte region [ffff888061fd8680, ffff888061fd8940) The buggy address belongs to the physical page: page:ffffea000187f600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x61fd8 head:ffffea000187f600 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000000840 ffff88801d674280 ffffea0002035700 dead000000000004 raw: 0000000000000000 0000000000130013 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 7264, tgid 7262 (syz.2.458), ts 196559225623, free_ts 184163219508 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582 prep_new_page mm/page_alloc.c:1589 [inline] get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501 alloc_slab_page+0x5d/0x180 mm/slub.c:1881 allocate_slab mm/slub.c:2028 [inline] new_slab+0x87/0x2d0 mm/slub.c:2081 ___slab_alloc+0xc5c/0x12f0 mm/slub.c:3253 __slab_alloc mm/slub.c:3339 [inline] __slab_alloc_node mm/slub.c:3392 [inline] slab_alloc_node mm/slub.c:3485 [inline] kmem_cache_alloc_node+0x12e/0x310 mm/slub.c:3540 kmalloc_reserve+0x95/0x240 net/core/skbuff.c:562 __alloc_skb+0x138/0x2c0 net/core/skbuff.c:653 alloc_skb include/linux/skbuff.h:1316 [inline] alloc_skb_with_frags+0xcd/0x7a0 net/core/skbuff.c:6353 sock_alloc_send_pskb+0x883/0x9a0 net/core/sock.c:2830 sock_alloc_send_skb include/net/sock.h:1954 [inline] __ip_append_data+0x2a08/0x3bf0 net/ipv4/ip_output.c:1127 ip_make_skb+0x22b/0x440 net/ipv4/ip_output.c:1566 udp_sendmsg+0x1ae1/0x23d0 net/ipv4/udp.c:1265 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x61b/0x980 net/socket.c:2595 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2649 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1182 [inline] free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459 free_large_kmalloc+0x101/0x1b0 mm/slab_common.c:984 bpf_check+0x6457/0xec30 kernel/bpf/verifier.c:20735 bpf_prog_load+0x10fa/0x1610 kernel/bpf/syscall.c:2753 __sys_bpf+0x5ba/0x890 kernel/bpf/syscall.c:5478 __do_sys_bpf kernel/bpf/syscall.c:5582 [inline] __se_sys_bpf kernel/bpf/syscall.c:5580 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5580 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Memory state around the buggy address: ffff888061fd8600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888061fd8680: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888061fd8700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888061fd8780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888061fd8800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================