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BUG: KASAN: use-after-free in memcpy include/linux/string.h:380 [inline]
BUG: KASAN: use-after-free in soft_cursor+0x439/0xa30 drivers/video/fbdev/core/softcursor.c:70
Read of size 32 at addr ffff8880a8242fd0 by task syz-executor.1/24455

CPU: 0 PID: 24455 Comm: syz-executor.1 Not tainted 5.5.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:639
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192
 memcpy+0x24/0x50 mm/kasan/common.c:125
 memcpy include/linux/string.h:380 [inline]
 soft_cursor+0x439/0xa30 drivers/video/fbdev/core/softcursor.c:70
 bit_cursor+0x12fc/0x1a60 drivers/video/fbdev/core/bitblit.c:386
 fbcon_cursor+0x487/0x660 drivers/video/fbdev/core/fbcon.c:1402
 hide_cursor+0x9d/0x2b0 drivers/tty/vt/vt.c:895
 redraw_screen+0x60b/0x7d0 drivers/tty/vt/vt.c:988
 vc_do_resize+0x10c9/0x1460 drivers/tty/vt/vt.c:1284
 vc_resize+0x4d/0x60 drivers/tty/vt/vt.c:1304
 vt_ioctl+0x2076/0x26d0 drivers/tty/vt/vt_ioctl.c:887
 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:545 [inline]
 do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a919
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc1c6e5cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 0000000020000000 RSI: 000000000000560a RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc1c6e5d6d4
R13: 00000000004c6ffc R14: 00000000004dd788 R15: 00000000ffffffff

Allocated by task 13655:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527
 __do_kmalloc_node mm/slab.c:3616 [inline]
 __kmalloc_node_track_caller+0x4e/0x70 mm/slab.c:3630
 __kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:141
 __alloc_skb+0x10b/0x5e0 net/core/skbuff.c:209
 alloc_skb include/linux/skbuff.h:1049 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:321 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:373 [inline]
 nsim_dev_trap_report_work+0x25c/0xaf0 drivers/net/netdevsim/dev.c:412
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264
 worker_thread+0x98/0xe40 kernel/workqueue.c:2410
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 13655:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:335 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 skb_free_head+0x93/0xb0 net/core/skbuff.c:591
 skb_release_data+0x551/0x8d0 net/core/skbuff.c:611
 skb_release_all+0x4d/0x60 net/core/skbuff.c:665
 __kfree_skb net/core/skbuff.c:679 [inline]
 consume_skb net/core/skbuff.c:838 [inline]
 consume_skb+0xfb/0x410 net/core/skbuff.c:832
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:387 [inline]
 nsim_dev_trap_report_work+0x7cb/0xaf0 drivers/net/netdevsim/dev.c:412
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264
 worker_thread+0x98/0xe40 kernel/workqueue.c:2410
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8880a8242000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 4048 bytes inside of
 4096-byte region [ffff8880a8242000, ffff8880a8243000)
The buggy address belongs to the page:
page:ffffea0002a09080 refcount:1 mapcount:0 mapping:ffff8880aa402000 index:0x0 compound_mapcount: 0
raw: 00fffe0000010200 ffffea0002959108 ffffea00015ec808 ffff8880aa402000
raw: 0000000000000000 ffff8880a8242000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a8242e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a8242f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a8242f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff8880a8243000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a8243080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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