================================================================== BUG: KASAN: use-after-free in fb_pad_unaligned_buffer+0x22e/0x500 drivers/video/fbdev/core/fbmem.c:110 Read of size 1 at addr ffff88803860c2a0 by task syz.0.4107/12863 CPU: 0 UID: 49663 PID: 12863 Comm: syz.0.4107 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 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 fb_pad_unaligned_buffer+0x22e/0x500 drivers/video/fbdev/core/fbmem.c:110 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:129 [inline] bit_putcs+0x950/0x1a50 drivers/video/fbdev/core/bitblit.c:187 fbcon_putcs+0x3a6/0x580 drivers/video/fbdev/core/fbcon.c:1320 con_flush drivers/tty/vt/vt.c:2801 [inline] do_con_write+0x2849/0x5210 drivers/tty/vt/vt.c:3227 con_write+0x24/0x40 drivers/tty/vt/vt.c:3565 process_output_block drivers/tty/n_tty.c:561 [inline] n_tty_write+0xd27/0x1200 drivers/tty/n_tty.c:2377 iterate_tty_write drivers/tty/tty_io.c:1006 [inline] file_tty_write+0x559/0xa20 drivers/tty/tty_io.c:1081 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f278058ec29 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:00007f2781403038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f27807d5fa0 RCX: 00007f278058ec29 RDX: 0000000000001006 RSI: 0000200000002100 RDI: 0000000000000006 RBP: 00007f2780611e41 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f27807d6038 R14: 00007f27807d5fa0 R15: 00007fff39d48f48 The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803860dd40 pfn:0x3860c flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 ffffea0001c81408 ffffea0000d21308 0000000000000000 raw: ffff88803860dd40 0000000000130000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as freed page last allocated via order 2, migratetype Unmovable, gfp_mask 0xf2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_MEMALLOC|__GFP_COMP|__GFP_NOMEMALLOC), pid 0, tgid 0 (swapper/0), ts 866130558691, free_ts 893680260342 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+0x21e4/0x22c0 mm/page_alloc.c:3869 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5159 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:3023 [inline] allocate_slab+0x96/0x3a0 mm/slub.c:3196 new_slab mm/slub.c:3250 [inline] ___slab_alloc+0xe94/0x1920 mm/slub.c:4626 __slab_alloc+0x65/0x100 mm/slub.c:4745 __slab_alloc_node mm/slub.c:4821 [inline] slab_alloc_node mm/slub.c:5232 [inline] kmem_cache_alloc_node_noprof+0x4c5/0x710 mm/slub.c:5296 kmalloc_reserve+0xbd/0x290 net/core/skbuff.c:579 __alloc_skb+0x142/0x2d0 net/core/skbuff.c:670 __netdev_alloc_skb+0x108/0x970 net/core/skbuff.c:734 netdev_alloc_skb include/linux/skbuff.h:3478 [inline] dev_alloc_skb include/linux/skbuff.h:3491 [inline] __ieee80211_beacon_get+0xc06/0x1880 net/mac80211/tx.c:5652 ieee80211_beacon_get_tim+0xb4/0x2b0 net/mac80211/tx.c:5774 ieee80211_beacon_get include/net/mac80211.h:5667 [inline] mac80211_hwsim_beacon_tx+0x3ce/0x860 drivers/net/wireless/virtual/mac80211_hwsim.c:2355 __iterate_interfaces+0x2ab/0x590 net/mac80211/util.c:761 ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:797 page last free pid 10760 tgid 10760 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1394 [inline] __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2906 __slab_free+0x2e7/0x390 mm/slub.c:5922 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:352 kasan_slab_alloc include/linux/kasan.h:252 [inline] slab_post_alloc_hook mm/slub.c:4945 [inline] slab_alloc_node mm/slub.c:5244 [inline] kmem_cache_alloc_noprof+0x367/0x6e0 mm/slub.c:5251 ptlock_alloc+0x20/0x70 mm/memory.c:7333 ptlock_init include/linux/mm.h:3062 [inline] pagetable_pte_ctor include/linux/mm.h:3116 [inline] __pte_alloc_one_noprof include/asm-generic/pgalloc.h:78 [inline] pte_alloc_one+0x7a/0x310 arch/x86/mm/pgtable.c:18 __pte_alloc+0x25/0x1a0 mm/memory.c:452 copy_pte_range mm/memory.c:1235 [inline] copy_pmd_range+0x7805/0x7f00 mm/memory.c:1389 copy_pud_range mm/memory.c:1426 [inline] copy_p4d_range mm/memory.c:1450 [inline] copy_page_range+0xc14/0x1270 mm/memory.c:1538 dup_mmap+0xf4c/0x1b10 mm/mmap.c:1834 dup_mm kernel/fork.c:1504 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1556 copy_process+0x1706/0x3c00 kernel/fork.c:2196 kernel_clone+0x21e/0x840 kernel/fork.c:2624 __do_sys_clone kernel/fork.c:2765 [inline] __se_sys_clone kernel/fork.c:2749 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2749 Memory state around the buggy address: ffff88803860c180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88803860c200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff88803860c280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88803860c300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88803860c380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ==================================================================