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BUG: KASAN: use-after-free in __fb_pad_aligned_buffer include/linux/fb.h:654 [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+0xbb6/0xd20 drivers/video/fbdev/core/bitblit.c:185
Read of size 1 at addr ffff88809a1eb8fe by task syz-executor.4/13657

CPU: 1 PID: 13657 Comm: syz-executor.4 Not tainted 5.9.0-rc6-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+0x198/0x1fd lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 __fb_pad_aligned_buffer include/linux/fb.h:654 [inline]
 bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
 bit_putcs+0xbb6/0xd20 drivers/video/fbdev/core/bitblit.c:185
 fbcon_putcs+0x35a/0x450 drivers/video/fbdev/core/fbcon.c:1308
 con_flush drivers/tty/vt/vt.c:2575 [inline]
 vc_con_write_normal drivers/tty/vt/vt.c:2803 [inline]
 do_con_write+0xfab/0x1dd0 drivers/tty/vt/vt.c:2910
 con_write+0x22/0xb0 drivers/tty/vt/vt.c:3250
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x3ce/0xf80 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x4d9/0x870 drivers/tty/tty_io.c:1046
 vfs_write+0x2b0/0x730 fs/read_write.c:576
 ksys_write+0x12d/0x250 fs/read_write.c:631
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45e179
Code: 3d b2 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 0b b2 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f21f68e7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000000393c0 RCX: 000000000045e179
RDX: 0000000000001006 RSI: 0000000020000180 RDI: 0000000000000004
RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffd3994195f R14: 00007f21f68e89c0 R15: 000000000118cf4c

Allocated by task 12565:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xae/0x550 net/core/skbuff.c:210
 alloc_skb_fclone include/linux/skbuff.h:1144 [inline]
 sk_stream_alloc_skb+0x109/0xc30 net/ipv4/tcp.c:884
 tcp_sendmsg_locked+0xbb7/0x2d20 net/ipv4/tcp.c:1291
 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1441
 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:817
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 __sys_sendto+0x21c/0x320 net/socket.c:1992
 __do_sys_sendto net/socket.c:2004 [inline]
 __se_sys_sendto net/socket.c:2000 [inline]
 __x64_sys_sendto+0xdd/0x1b0 net/socket.c:2000
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88809a1eb800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 254 bytes inside of
 1024-byte region [ffff88809a1eb800, ffff88809a1ebc00)
The buggy address belongs to the page:
page:00000000dd9ac5e8 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88809a1eb800 pfn:0x9a1eb
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002433f48 ffffea0002786f88 ffff8880aa040700
raw: ffff88809a1eb800 ffff88809a1eb000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809a1eb780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809a1eb800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809a1eb880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff88809a1eb900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809a1eb980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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