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BUG: KASAN: slab-out-of-bounds in __fb_pad_aligned_buffer include/linux/fb.h:655 [inline]
BUG: KASAN: slab-out-of-bounds in fb_pad_aligned_buffer+0x137/0x150 drivers/video/fbdev/core/fbmem.c:116
Read of size 1 at addr ffff88803f7f6b20 by task syz-executor.1/7491

CPU: 0 PID: 7491 Comm: syz-executor.1 Not tainted 5.7.0-rc7-next-20200529-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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x413 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:655 [inline]
 fb_pad_aligned_buffer+0x137/0x150 drivers/video/fbdev/core/fbmem.c:116
 bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:99 [inline]
 bit_putcs+0xbb4/0xd60 drivers/video/fbdev/core/bitblit.c:185
 fbcon_putcs+0x345/0x3f0 drivers/video/fbdev/core/fbcon.c:1362
 do_update_region+0x398/0x630 drivers/tty/vt/vt.c:683
 redraw_screen+0x64c/0x770 drivers/tty/vt/vt.c:1029
 vc_do_resize+0x1007/0x1370 drivers/tty/vt/vt.c:1314
 vt_ioctl+0x200c/0x2640 drivers/tty/vt/vt_ioctl.c:901
 tty_ioctl+0xedc/0x1440 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45ca69
Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3c4b1bec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004f3080 RCX: 000000000045ca69
RDX: 0000000020000000 RSI: 000000000000560a RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000067a R14: 00000000004c975b R15: 00007f3c4b1bf6d4

Allocated by task 3758:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc mm/kasan/common.c:494 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x161/0x7a0 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 fbcon_set_font+0x331/0x870 drivers/video/fbdev/core/fbcon.c:2672
 con_font_set drivers/tty/vt/vt.c:4571 [inline]
 con_font_op+0xd65/0x1160 drivers/tty/vt/vt.c:4636
 vt_ioctl+0x1740/0x2640 drivers/tty/vt/vt_ioctl.c:980
 tty_ioctl+0xedc/0x1440 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff88803f7f6000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 2848 bytes inside of
 4096-byte region [ffff88803f7f6000, ffff88803f7f7000)
The buggy address belongs to the page:
page:ffffea0000fdfd80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0000fdfd80 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0001728b88 ffffea00029aba08 ffff8880aa002000
raw: 0000000000000000 ffff88803f7f6000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88803f7f6a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88803f7f6a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88803f7f6b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                               ^
 ffff88803f7f6b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88803f7f6c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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