================================================================== BUG: KASAN: use-after-free in memcpy include/linux/string.h:381 [inline] BUG: KASAN: use-after-free in soft_cursor+0x448/0xa20 drivers/video/fbdev/core/softcursor.c:70 Read of size 32 at addr ffff88809192d810 by task syz-executor.4/1757 CPU: 1 PID: 1757 Comm: syz-executor.4 Not tainted 5.7.0-rc3-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+0x188/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:382 __kasan_report.cold+0x35/0x4d mm/kasan/report.c:511 kasan_report+0x33/0x50 mm/kasan/common.c:625 check_memory_region_inline mm/kasan/generic.c:187 [inline] check_memory_region+0x141/0x190 mm/kasan/generic.c:193 memcpy+0x20/0x60 mm/kasan/common.c:106 memcpy include/linux/string.h:381 [inline] soft_cursor+0x448/0xa20 drivers/video/fbdev/core/softcursor.c:70 bit_cursor+0x1230/0x1900 drivers/video/fbdev/core/bitblit.c:386 fbcon_cursor+0x477/0x650 drivers/video/fbdev/core/fbcon.c:1411 hide_cursor+0x85/0x280 drivers/tty/vt/vt.c:897 redraw_screen+0x5e1/0x770 drivers/tty/vt/vt.c:1001 fbcon_do_set_font+0x815/0x950 drivers/video/fbdev/core/fbcon.c:2614 fbcon_copy_font+0x125/0x190 drivers/video/fbdev/core/fbcon.c:2629 con_font_copy drivers/tty/vt/vt.c:4622 [inline] con_font_op+0x666/0x1160 drivers/tty/vt/vt.c:4637 vt_ioctl+0x1793/0x26b0 drivers/tty/vt/vt_ioctl.c:980 tty_ioctl+0xedc/0x1440 drivers/tty/tty_io.c:2656 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x11a/0x180 fs/ioctl.c:763 __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl fs/ioctl.c:770 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c829 Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f8554491c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004e65c0 RCX: 000000000045c829 RDX: 0000000020000880 RSI: 0000000000004b72 RDI: 0000000000000003 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000036c R14: 00000000004c5dcb R15: 00007f85544926d4 Allocated by task 15272: save_stack+0x1b/0x40 mm/kasan/common.c:49 set_track mm/kasan/common.c:57 [inline] __kasan_kmalloc mm/kasan/common.c:495 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468 __kmalloc_reserve.isra.0+0x39/0xe0 net/core/skbuff.c:142 pskb_expand_head+0x148/0x1020 net/core/skbuff.c:1627 skb_ensure_writable net/core/skbuff.c:5459 [inline] skb_ensure_writable+0x2b4/0x450 net/core/skbuff.c:5451 __bpf_try_make_writable net/core/filter.c:1635 [inline] bpf_try_make_writable net/core/filter.c:1641 [inline] bpf_try_make_head_writable net/core/filter.c:1649 [inline] ____bpf_clone_redirect net/core/filter.c:2134 [inline] bpf_clone_redirect+0x12c/0x430 net/core/filter.c:2112 0xffffffffa004ea04 bpf_dispatcher_nop_func include/linux/bpf.h:545 [inline] bpf_test_run+0x3c4/0xc70 net/bpf/test_run.c:49 bpf_prog_test_run_skb+0xafc/0x1520 net/bpf/test_run.c:438 bpf_prog_test_run kernel/bpf/syscall.c:2769 [inline] __do_sys_bpf+0x22f2/0x4370 kernel/bpf/syscall.c:3726 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Freed by task 15272: save_stack+0x1b/0x40 mm/kasan/common.c:49 set_track mm/kasan/common.c:57 [inline] kasan_set_free_info mm/kasan/common.c:317 [inline] __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456 __cache_free mm/slab.c:3426 [inline] kfree+0x109/0x2b0 mm/slab.c:3757 skb_free_head+0x8b/0xa0 net/core/skbuff.c:590 skb_release_data+0x42e/0x8b0 net/core/skbuff.c:610 skb_release_all+0x46/0x60 net/core/skbuff.c:664 __kfree_skb net/core/skbuff.c:678 [inline] kfree_skb net/core/skbuff.c:696 [inline] kfree_skb+0xfa/0x410 net/core/skbuff.c:690 batadv_send_skb_unicast+0x18b/0x1f0 net/batman-adv/send.c:383 batadv_send_skb_via_tt_generic+0x8c/0xe0 net/batman-adv/send.c:425 batadv_send_skb_via_tt net/batman-adv/send.h:82 [inline] batadv_interface_tx+0x1297/0x1620 net/batman-adv/soft-interface.c:378 __netdev_start_xmit include/linux/netdevice.h:4533 [inline] netdev_start_xmit include/linux/netdevice.h:4547 [inline] xmit_one net/core/dev.c:3477 [inline] dev_hard_start_xmit+0x1a4/0x9b0 net/core/dev.c:3493 __dev_queue_xmit+0x25e1/0x30a0 net/core/dev.c:4052 __bpf_tx_skb net/core/filter.c:2061 [inline] __bpf_redirect_common net/core/filter.c:2100 [inline] __bpf_redirect+0x769/0xc60 net/core/filter.c:2107 ____bpf_clone_redirect net/core/filter.c:2140 [inline] bpf_clone_redirect+0x2b7/0x430 net/core/filter.c:2112 0xffffffffa004ea04 bpf_dispatcher_nop_func include/linux/bpf.h:545 [inline] bpf_test_run+0x3c4/0xc70 net/bpf/test_run.c:49 bpf_prog_test_run_skb+0xafc/0x1520 net/bpf/test_run.c:438 bpf_prog_test_run kernel/bpf/syscall.c:2769 [inline] __do_sys_bpf+0x22f2/0x4370 kernel/bpf/syscall.c:3726 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 The buggy address belongs to the object at ffff88809192d800 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 16 bytes inside of 512-byte region [ffff88809192d800, ffff88809192da00) The buggy address belongs to the page: page:ffffea0002464b40 refcount:1 mapcount:0 mapping:00000000bf60353d index:0xffff88809192d800 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea0002a406c8 ffffea0002a34f88 ffff8880aa000a80 raw: ffff88809192d800 ffff88809192d000 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809192d700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88809192d780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88809192d800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88809192d880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809192d900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================