syzbot

overlayfs: missing 'workdir'
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BUG: KASAN: slab-out-of-bounds in fb_pad_unaligned_buffer+0x43c/0x470 drivers/video/fbdev/core/fbmem.c:116
Read of size 1 at addr ffff88804f6f89f0 by task syz.0.972/9597

CPU: 2 UID: 0 PID: 9597 Comm: syz.0.972 Not tainted 6.12.0-syzkaller-11677-g2ba9f676d0a2 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
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:378 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:489
 kasan_report+0xd9/0x110 mm/kasan/report.c:602
 fb_pad_unaligned_buffer+0x43c/0x470 drivers/video/fbdev/core/fbmem.c:116
 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:130 [inline]
 bit_putcs+0x86a/0xdf0 drivers/video/fbdev/core/bitblit.c:188
 fbcon_putcs+0x364/0x480 drivers/video/fbdev/core/fbcon.c:1308
 do_update_region+0x1f8/0x3f0 drivers/tty/vt/vt.c:609
 update_region+0xc1/0x160 drivers/tty/vt/vt.c:633
 vcs_write+0x7cd/0xdb0 drivers/tty/vt/vc_screen.c:698
 do_loop_readv_writev fs/read_write.c:843 [inline]
 do_loop_readv_writev fs/read_write.c:828 [inline]
 vfs_writev+0x6da/0xdd0 fs/read_write.c:1052
 do_writev+0x133/0x340 fs/read_write.c:1096
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe507b80849
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:00007fe508a48058 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fe507d45fa0 RCX: 00007fe507b80849
RDX: 0000000000000002 RSI: 0000000020000480 RDI: 0000000000000004
RBP: 00007fe507bf3986 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe507d45fa0 R15: 00007ffc25c9b828
 </TASK>

Allocated by task 6851:
 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:4283 [inline]
 __kmalloc_noprof+0x21c/0x510 mm/slub.c:4295
 kmalloc_noprof include/linux/slab.h:905 [inline]
 fbcon_set_font+0x434/0xb60 drivers/video/fbdev/core/fbcon.c:2516
 con_font_set drivers/tty/vt/vt.c:4804 [inline]
 con_font_op+0x7fd/0xf50 drivers/tty/vt/vt.c:4851
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
 vt_ioctl+0x4ca/0x2f80 drivers/tty/vt/vt_ioctl.c:751
 tty_ioctl+0x651/0x15d0 drivers/tty/tty_io.c:2803
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88804f6f8000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 480 bytes to the right of
 allocated 2064-byte region [ffff88804f6f8000, ffff88804f6f8810)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4f6f8
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 ffff88801b043040 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000040004 00000001f5000000 0000000000000000
head: 00fff00000000040 ffff88801b043040 dead000000000100 dead000000000122
head: 0000000000000000 0000000000040004 00000001f5000000 0000000000000000
head: 00fff00000000003 ffffea00013dbe01 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 12, tgid 12 (kworker/u32:1), ts 50836393947, free_ts 50626313760
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x2d1/0x350 mm/page_alloc.c:1556
 prep_new_page mm/page_alloc.c:1564 [inline]
 get_page_from_freelist+0xfce/0x2f80 mm/page_alloc.c:3474
 __alloc_pages_noprof+0x223/0x25b0 mm/page_alloc.c:4751
 alloc_pages_mpol_noprof+0x2c9/0x610 mm/mempolicy.c:2265
 alloc_slab_page mm/slub.c:2408 [inline]
 allocate_slab mm/slub.c:2574 [inline]
 new_slab+0x2c9/0x410 mm/slub.c:2627
 ___slab_alloc+0xdac/0x1870 mm/slub.c:3815
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3905
 __slab_alloc_node mm/slub.c:3980 [inline]
 slab_alloc_node mm/slub.c:4141 [inline]
 __do_kmalloc_node mm/slub.c:4282 [inline]
 __kmalloc_node_track_caller_noprof+0x2f1/0x510 mm/slub.c:4302
 kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:609
 __alloc_skb+0x164/0x380 net/core/skbuff.c:678
 alloc_skb include/linux/skbuff.h:1323 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x2af/0xd00 drivers/net/netdevsim/dev.c:851
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
 process_scheduled_works kernel/workqueue.c:3310 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
page last free pid 30 tgid 30 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_page+0x661/0x1080 mm/page_alloc.c:2657
 __put_partials+0x14c/0x170 mm/slub.c:3142
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4e/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:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4104 [inline]
 slab_alloc_node mm/slub.c:4153 [inline]
 __kmalloc_cache_noprof+0x243/0x410 mm/slub.c:4309
 kmalloc_noprof include/linux/slab.h:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 nsim_fib6_rt_create drivers/net/netdevsim/fib.c:547 [inline]
 nsim_fib6_rt_insert drivers/net/netdevsim/fib.c:752 [inline]
 nsim_fib6_event drivers/net/netdevsim/fib.c:856 [inline]
 nsim_fib_event drivers/net/netdevsim/fib.c:889 [inline]
 nsim_fib_event_work+0x1384/0x26d0 drivers/net/netdevsim/fib.c:1493
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
 process_scheduled_works kernel/workqueue.c:3310 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
 ffff88804f6f8880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88804f6f8900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88804f6f8980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                             ^
 ffff88804f6f8a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88804f6f8a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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