kobject: 'nullb0' (00000000cdb13351): kobject_uevent_env kobject: 'nullb0' (00000000cdb13351): fill_kobj_path: path = '/devices/virtual/block/nullb0' kobject: 'loop1' (00000000f4feea79): kobject_uevent_env kobject: 'loop1' (00000000f4feea79): fill_kobj_path: path = '/devices/virtual/block/loop1' ================================================================== BUG: KASAN: use-after-free in memcpy include/linux/string.h:348 [inline] BUG: KASAN: use-after-free in soft_cursor+0x439/0xa30 drivers/video/fbdev/core/softcursor.c:70 Read of size 3 at addr ffff88809b54e34a by task syz-executor.0/17392 CPU: 1 PID: 17392 Comm: syz-executor.0 Not tainted 4.19.91-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.cold+0x7c/0x20d mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x123/0x190 mm/kasan/kasan.c:267 memcpy+0x24/0x50 mm/kasan/kasan.c:302 memcpy include/linux/string.h:348 [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+0x58a/0x7b0 drivers/video/fbdev/core/fbcon.c:1369 hide_cursor+0x9e/0x300 drivers/tty/vt/vt.c:895 redraw_screen+0x2ee/0x8e0 drivers/tty/vt/vt.c:988 vc_do_resize+0x118e/0x14a0 drivers/tty/vt/vt.c:1287 vc_resize+0x4d/0x60 drivers/tty/vt/vt.c:1307 vt_ioctl+0x1fe0/0x2530 drivers/tty/vt/vt_ioctl.c:887 tty_ioctl+0x7f3/0x1510 drivers/tty/tty_io.c:2669 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688 ksys_ioctl+0xab/0xd0 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 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:00007ff0529f3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919 RDX: 0000000020000040 RSI: 000000000000560a RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff0529f46d4 R13: 00000000004c6ffc R14: 00000000004dd7a8 R15: 00000000ffffffff Allocated by task 17199: save_stack+0x45/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc mm/kasan/kasan.c:553 [inline] kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531 __do_kmalloc_node mm/slab.c:3689 [inline] __kmalloc_node_track_caller+0x51/0x80 mm/slab.c:3703 __kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:137 __alloc_skb+0x10b/0x5f0 net/core/skbuff.c:205 alloc_skb include/linux/skbuff.h:995 [inline] __ip6_append_data.isra.0+0x23b7/0x2fb0 net/ipv6/ip6_output.c:1428 ip6_append_data+0x1ec/0x330 net/ipv6/ip6_output.c:1590 rawv6_sendmsg+0x13fb/0x33d0 net/ipv6/raw.c:950 inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:798 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:632 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2115 __sys_sendmmsg+0x1bf/0x4e0 net/socket.c:2210 __do_sys_sendmmsg net/socket.c:2239 [inline] __se_sys_sendmmsg net/socket.c:2236 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2236 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 17199: save_stack+0x45/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kfree+0xcf/0x220 mm/slab.c:3822 skb_free_head+0x99/0xc0 net/core/skbuff.c:554 skb_release_data+0x619/0x8d0 net/core/skbuff.c:574 skb_release_all+0x4d/0x60 net/core/skbuff.c:631 __kfree_skb net/core/skbuff.c:645 [inline] consume_skb net/core/skbuff.c:705 [inline] consume_skb+0xe2/0x390 net/core/skbuff.c:699 ip6_input_finish+0xcf2/0x17c0 net/ipv6/ip6_input.c:422 NF_HOOK include/linux/netfilter.h:289 [inline] NF_HOOK include/linux/netfilter.h:283 [inline] ip6_input+0xe4/0x3f0 net/ipv6/ip6_input.c:438 dst_input include/net/dst.h:453 [inline] ip6_rcv_finish+0x1de/0x2f0 net/ipv6/ip6_input.c:76 NF_HOOK include/linux/netfilter.h:289 [inline] NF_HOOK include/linux/netfilter.h:283 [inline] ipv6_rcv+0x119/0x430 net/ipv6/ip6_input.c:283 __netif_receive_skb_one_core+0x113/0x1a0 net/core/dev.c:4946 __netif_receive_skb+0x2c/0x1d0 net/core/dev.c:5058 process_backlog+0x206/0x750 net/core/dev.c:5869 napi_poll net/core/dev.c:6292 [inline] net_rx_action+0x4f5/0x1070 net/core/dev.c:6358 __do_softirq+0x25c/0x921 kernel/softirq.c:292 The buggy address belongs to the object at ffff88809b54e2c0 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 138 bytes inside of 512-byte region [ffff88809b54e2c0, ffff88809b54e4c0) The buggy address belongs to the page: page:ffffea00026d5380 count:1 mapcount:0 mapping:ffff88812c31c940 index:0x0 flags: 0xfffe0000000100(slab) raw: 00fffe0000000100 ffffea0002798f48 ffffea0002645288 ffff88812c31c940 raw: 0000000000000000 ffff88809b54e040 0000000100000006 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809b54e200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88809b54e280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb >ffff88809b54e300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88809b54e380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809b54e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================