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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+0xb3a/0xcd0 drivers/video/fbdev/core/bitblit.c:185
Read of size 1 at addr ffff8880a8d333ca by task syz-executor.5/24116

CPU: 1 PID: 24116 Comm: syz-executor.5 Not tainted 4.14.175-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+0x13e/0x194 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1e2 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+0xa9/0x2ae 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+0xb3a/0xcd0 drivers/video/fbdev/core/bitblit.c:185
 fbcon_putcs+0x3c6/0x490 drivers/video/fbdev/core/fbcon.c:1298
 do_update_region+0x34b/0x5b0 drivers/tty/vt/vt.c:373
 redraw_screen+0x561/0x770 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+0x6c5/0x1220 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+0x42/0xb7
RIP: 0033:0x45c889
RSP: 002b:00007fcf651c7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fcf651c86d4 RCX: 000000000045c889
RDX: 0000000020000040 RSI: 000000000000560a RDI: 0000000000000003
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000066a R14: 00000000004c9426 R15: 000000000076bf0c

Allocated by task 22778:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 __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
 skb_copy+0x134/0x2f0 net/core/skbuff.c:1345
 batadv_add_bcast_packet_to_list+0x19a/0x5a0 net/batman-adv/send.c:761
 batadv_interface_tx+0xeab/0x1200 net/batman-adv/soft-interface.c:346
 __netdev_start_xmit include/linux/netdevice.h:4039 [inline]
 netdev_start_xmit include/linux/netdevice.h:4048 [inline]
 xmit_one net/core/dev.c:3009 [inline]
 dev_hard_start_xmit+0x186/0x890 net/core/dev.c:3025
 __dev_queue_xmit+0x1d91/0x25c0 net/core/dev.c:3525
 __bpf_tx_skb net/core/filter.c:1708 [inline]
 __bpf_redirect_common net/core/filter.c:1747 [inline]
 __bpf_redirect+0x5e6/0xa30 net/core/filter.c:1754
 ____bpf_clone_redirect net/core/filter.c:1787 [inline]
 bpf_clone_redirect+0x1f4/0x2d0 net/core/filter.c:1759
 bpf_prog_bb15b996d00816f9+0xa70/0x1000

Freed by task 221:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 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+0x528/0x7b0 net/core/skbuff.c:574
 skb_release_all+0x46/0x60 net/core/skbuff.c:631
 __kfree_skb net/core/skbuff.c:645 [inline]
 consume_skb+0xa7/0x330 net/core/skbuff.c:705
 batadv_forw_packet_free+0x12f/0x180 net/batman-adv/send.c:468
 batadv_send_outstanding_bcast_packet+0x534/0x780 net/batman-adv/send.c:952
 process_one_work+0x813/0x1540 kernel/workqueue.c:2116
 worker_thread+0x5d1/0x1070 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff8880a8d33340
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 138 bytes inside of
 512-byte region [ffff8880a8d33340, ffff8880a8d33540)
The buggy address belongs to the page:
page:ffffea0002a34cc0 count:1 mapcount:0 mapping:ffff8880a8d330c0 index:0xffff8880a8d33340
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880a8d330c0 ffff8880a8d33340 0000000100000002
raw: ffffea00026dd460 ffffea000236f1e0 ffff88812fe56940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a8d33280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a8d33300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880a8d33380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8880a8d33400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a8d33480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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