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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+0xab7/0xc30 drivers/video/fbdev/core/bitblit.c:185
Read of size 1 at addr ffff8880b313f3ca by task syz-executor.2/21535

CPU: 0 PID: 21535 Comm: syz-executor.2 Not tainted 4.14.223-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+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load1_noabort+0x68/0x70 mm/kasan/report.c:427
 __fb_pad_aligned_buffer include/linux/fb.h:663 [inline]
 bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
 bit_putcs+0xab7/0xc30 drivers/video/fbdev/core/bitblit.c:185
 fbcon_putcs+0x2fe/0x480 drivers/video/fbdev/core/fbcon.c:1247
 con_flush drivers/tty/vt/vt.c:2206 [inline]
 do_con_write+0x908/0x19b0 drivers/tty/vt/vt.c:2410
 con_write+0x21/0xa0 drivers/tty/vt/vt.c:2805
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x352/0xda0 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:959 [inline]
 tty_write+0x410/0x740 drivers/tty/tty_io.c:1043
 __vfs_write+0xe4/0x630 fs/read_write.c:480
 vfs_write+0x17f/0x4d0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xf2/0x210 fs/read_write.c:582
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x465ef9
RSP: 002b:00007f5a6c84c188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465ef9
RDX: 0000000000001006 RSI: 0000000020000000 RDI: 0000000000000005
RBP: 00000000004bfa34 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffd3d71b3df R14: 00007f5a6c84c300 R15: 0000000000022000

Allocated by task 20232:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 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 net/core/skbuff.c:137 [inline]
 __alloc_skb+0x96/0x510 net/core/skbuff.c:205
 alloc_skb include/linux/skbuff.h:980 [inline]
 sock_wmalloc+0xa5/0xf0 net/core/sock.c:1935
 __ip6_append_data.isra.0+0x2163/0x2860 net/ipv6/ip6_output.c:1464
 ip6_append_data+0x1b8/0x2f0 net/ipv6/ip6_output.c:1620
 rawv6_sendmsg+0x10ae/0x2df0 net/ipv6/raw.c:952
 inet_sendmsg+0x11a/0x4e0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 ___sys_sendmsg+0x326/0x800 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 20237:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 skb_free_head net/core/skbuff.c:563 [inline]
 skb_release_data+0x5f6/0x820 net/core/skbuff.c:583
 skb_release_all net/core/skbuff.c:640 [inline]
 __kfree_skb net/core/skbuff.c:654 [inline]
 consume_skb+0xe0/0x380 net/core/skbuff.c:714
 skb_free_datagram+0x16/0xe0 net/core/datagram.c:331
 rawv6_recvmsg+0x881/0xb70 net/ipv6/raw.c:530
 sock_common_recvmsg+0xe1/0x170 net/core/sock.c:2978
 ___sys_recvmsg+0x20b/0x4d0 net/socket.c:2221
 __sys_recvmmsg+0x1f3/0x5d0 net/socket.c:2329
 SYSC_recvmmsg net/socket.c:2405 [inline]
 SyS_recvmmsg+0x125/0x140 net/socket.c:2394
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff8880b313f340
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 138 bytes inside of
 512-byte region [ffff8880b313f340, ffff8880b313f540)
The buggy address belongs to the page:
page:ffffea0002cc4fc0 count:1 mapcount:0 mapping:ffff8880b313f0c0 index:0xffff8880b313f5c0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880b313f0c0 ffff8880b313f5c0 0000000100000004
raw: ffffea00027c0360 ffffea000267f0e0 ffff88813fe80940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880b313f280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880b313f300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880b313f380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8880b313f400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880b313f480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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