syzbot

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BUG: KASAN: slab-out-of-bounds in scr_memcpyw include/linux/vt_buffer.h:38 [inline]
BUG: KASAN: slab-out-of-bounds in fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:613
Read of size 10 at addr ffff88807ca26bda by task syz.1.20/6073

CPU: 1 UID: 0 PID: 6073 Comm: syz.1.20 Not tainted 6.15.0-rc2-syzkaller-00471-g119009db2674 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __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:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189
 __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:613
 fbcon_init+0xd77/0x1900 drivers/video/fbdev/core/fbcon.c:1145
 visual_init+0x31d/0x620 drivers/tty/vt/vt.c:1011
 do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3831
 vt_bind drivers/tty/vt/vt.c:3987 [inline]
 store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059
 dev_attr_store+0x55/0x80 drivers/base/core.c:2440
 sysfs_kf_write+0xef/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x351/0x510 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x5ba/0x1180 fs/read_write.c:684
 ksys_write+0x12a/0x240 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f942938e169
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:00007f942a24f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f94295b6080 RCX: 00007f942938e169
RDX: 00000000fffffdef RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f9429410a68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f94295b6080 R15: 00007ffea6958018
 </TASK>

Allocated by task 6073:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4341 [inline]
 __kmalloc_noprof+0x223/0x510 mm/slub.c:4353
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 vc_do_resize+0x1de/0x10e0 drivers/tty/vt/vt.c:1174
 vc_resize include/linux/vt_kern.h:49 [inline]
 fbcon_init+0xd53/0x1900 drivers/video/fbdev/core/fbcon.c:1142
 visual_init+0x31d/0x620 drivers/tty/vt/vt.c:1011
 do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3831
 vt_bind drivers/tty/vt/vt.c:3987 [inline]
 store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059
 dev_attr_store+0x55/0x80 drivers/base/core.c:2440
 sysfs_kf_write+0xef/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x351/0x510 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x5ba/0x1180 fs/read_write.c:684
 ksys_write+0x12a/0x240 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88807ca26b80
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 20 bytes to the right of
 allocated 70-byte region [ffff88807ca26b80, ffff88807ca26bc6)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7ca26
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b441280 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080200020 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 3084, tgid 3084 (kworker/1:2), ts 119325463351, free_ts 109983997427
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1718
 prep_new_page mm/page_alloc.c:1726 [inline]
 get_page_from_freelist+0x135c/0x3920 mm/page_alloc.c:3700
 __alloc_frozen_pages_noprof+0x263/0x23a0 mm/page_alloc.c:4982
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2301
 alloc_slab_page mm/slub.c:2468 [inline]
 allocate_slab mm/slub.c:2632 [inline]
 new_slab+0x244/0x340 mm/slub.c:2686
 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3872
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3962
 __slab_alloc_node mm/slub.c:4037 [inline]
 slab_alloc_node mm/slub.c:4198 [inline]
 __kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4367
 kmalloc_noprof include/linux/slab.h:905 [inline]
 dst_cow_metrics_generic+0x4c/0x1e0 net/core/dst.c:193
 dst_metrics_write_ptr include/net/dst.h:133 [inline]
 dst_metric_set include/net/dst.h:194 [inline]
 icmp6_dst_alloc+0x415/0x4f0 net/ipv6/route.c:3328
 mld_sendpack+0x5a8/0x1220 net/ipv6/mcast.c:1857
 mld_send_initial_cr.part.0+0x1a1/0x260 net/ipv6/mcast.c:2285
 mld_send_initial_cr net/ipv6/mcast.c:2273 [inline]
 mld_dad_work+0x51/0x2d0 net/ipv6/mcast.c:2308
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:464
page last free pid 5914 tgid 5914 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_frozen_pages+0x69d/0xff0 mm/page_alloc.c:2725
 vfree+0x176/0x960 mm/vmalloc.c:3383
 kcov_put kernel/kcov.c:439 [inline]
 kcov_put kernel/kcov.c:435 [inline]
 kcov_close+0x34/0x60 kernel/kcov.c:535
 __fput+0x3ff/0xb70 fs/file_table.c:465
 task_work_run+0x14d/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xafb/0x2c30 kernel/exit.c:953
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7a0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x230 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88807ca26a80: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
 ffff88807ca26b00: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
>ffff88807ca26b80: 00 00 00 00 00 00 00 00 06 fc fc fc fc fc fc fc
                                                    ^
 ffff88807ca26c00: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
 ffff88807ca26c80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
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