================================================================== BUG: KASAN: use-after-free in __fb_pad_aligned_buffer include/linux/fb.h:663 [inline] BUG: KASAN: use-after-free in bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline] BUG: KASAN: use-after-free in bit_putcs+0xa8a/0xc00 drivers/video/fbdev/core/bitblit.c:185 Read of size 1 at addr ffff888088cf9e04 by task syz-executor.0/31307 CPU: 1 PID: 31307 Comm: syz-executor.0 Not tainted 4.14.181-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x283 lib/dump_stack.c:58 print_address_description.cold+0x54/0x1dc mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold+0xa9/0x2b9 mm/kasan/report.c:393 __fb_pad_aligned_buffer include/linux/fb.h:663 [inline] bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline] bit_putcs+0xa8a/0xc00 drivers/video/fbdev/core/bitblit.c:185 fbcon_putcs+0x3bb/0x480 drivers/video/fbdev/core/fbcon.c:1301 do_update_region+0x34b/0x5b0 drivers/tty/vt/vt.c:373 redraw_screen+0x562/0x760 drivers/tty/vt/vt.c:705 vc_do_resize+0xbe0/0xde0 drivers/tty/vt/vt.c:967 vt_ioctl+0x1a64/0x1f20 drivers/tty/vt/vt_ioctl.c:901 tty_ioctl+0x6c9/0x1220 drivers/tty/tty_io.c:2661 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45ca29 RSP: 002b:00007f7cc2c6cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004f2b00 RCX: 000000000045ca29 RDX: 0000000020000000 RSI: 000000000000560a RDI: 0000000000000003 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000673 R14: 00000000004c9681 R15: 00007f7cc2c6d6d4 Allocated by task 29049: save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551 __do_kmalloc_node mm/slab.c:3682 [inline] __kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3696 __kmalloc_reserve.isra.0+0x35/0xd0 net/core/skbuff.c:137 __alloc_skb+0xca/0x4c0 net/core/skbuff.c:205 alloc_skb include/linux/skbuff.h:980 [inline] alloc_skb_with_frags+0x85/0x500 net/core/skbuff.c:5228 sock_alloc_send_pskb+0x57b/0x6d0 net/core/sock.c:2081 __ip_append_data.isra.0+0x11e2/0x1ff0 net/ipv4/ip_output.c:972 ip_make_skb+0x169/0x1b0 net/ipv4/ip_output.c:1489 udp_sendmsg+0x152f/0x1b60 net/ipv4/udp.c:1052 udpv6_sendmsg+0x1393/0x2610 net/ipv6/udp.c:1193 inet_sendmsg+0x116/0x4d0 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xb5/0x100 net/socket.c:656 ___sys_sendmsg+0x349/0x840 net/socket.c:2062 __sys_sendmmsg+0x129/0x330 net/socket.c:2152 SYSC_sendmmsg net/socket.c:2183 [inline] SyS_sendmmsg+0x2f/0x50 net/socket.c:2178 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 29049: save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0xaf/0x190 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcb/0x260 mm/slab.c:3815 skb_free_head+0x83/0xa0 net/core/skbuff.c:554 skb_release_data+0x57e/0x7d0 net/core/skbuff.c:574 skb_release_all+0x46/0x60 net/core/skbuff.c:631 __kfree_skb net/core/skbuff.c:645 [inline] kfree_skb+0xae/0x340 net/core/skbuff.c:663 __udp4_lib_rcv+0x12a5/0x2780 net/ipv4/udp.c:2179 ip_local_deliver_finish+0x3f2/0xab0 net/ipv4/ip_input.c:216 NF_HOOK include/linux/netfilter.h:250 [inline] ip_local_deliver+0x167/0x460 net/ipv4/ip_input.c:257 dst_input include/net/dst.h:468 [inline] ip_rcv_finish+0x6e1/0x1a00 net/ipv4/ip_input.c:396 NF_HOOK include/linux/netfilter.h:250 [inline] ip_rcv+0x8d3/0xf3f net/ipv4/ip_input.c:493 __netif_receive_skb_core+0x1e8e/0x2c10 net/core/dev.c:4478 __netif_receive_skb+0x27/0x1a0 net/core/dev.c:4516 process_backlog+0x20c/0x760 net/core/dev.c:5198 napi_poll net/core/dev.c:5599 [inline] net_rx_action+0x456/0xe80 net/core/dev.c:5665 __do_softirq+0x254/0x9bf kernel/softirq.c:288 The buggy address belongs to the object at ffff888088cf9d00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 260 bytes inside of 512-byte region [ffff888088cf9d00, ffff888088cf9f00) The buggy address belongs to the page: page:ffffea0002233e40 count:1 mapcount:0 mapping:ffff888088cf9080 index:0xffff888088cf9a80 flags: 0xfffe0000000100(slab) raw: 00fffe0000000100 ffff888088cf9080 ffff888088cf9a80 0000000100000001 raw: ffffea0001ad3060 ffffea0002990a20 ffff8880aa800940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888088cf9d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888088cf9d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888088cf9e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888088cf9e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888088cf9f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================