syzbot

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BUG: KASAN: global-out-of-bounds in __fb_pad_aligned_buffer include/linux/fb.h:636 [inline]
BUG: KASAN: global-out-of-bounds in bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
BUG: KASAN: global-out-of-bounds in bit_putcs+0x147b/0x1db0 drivers/video/fbdev/core/bitblit.c:185
Read of size 1 at addr ffffffff8c630cd0 by task syz.7.3706/19043

CPU: 1 UID: 0 PID: 19043 Comm: syz.7.3706 Not tainted 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 __fb_pad_aligned_buffer include/linux/fb.h:636 [inline]
 bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
 bit_putcs+0x147b/0x1db0 drivers/video/fbdev/core/bitblit.c:185
 fbcon_putcs+0x2e0/0x450 drivers/video/fbdev/core/fbcon.c:1308
 do_update_region+0x205/0x450 drivers/tty/vt/vt.c:609
 update_region+0x1c2/0x490 drivers/tty/vt/vt.c:633
 vcs_write+0xdd6/0x12d0 drivers/tty/vt/vc_screen.c:698
 do_loop_readv_writev fs/read_write.c:857 [inline]
 vfs_writev+0x5a9/0xba0 fs/read_write.c:1066
 do_writev+0x1b1/0x350 fs/read_write.c:1111
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdb0b77e719
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fdb0c573038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fdb0b935f80 RCX: 00007fdb0b77e719
RDX: 0000000000000004 RSI: 0000000020000c40 RDI: 000000000000000d
RBP: 00007fdb0b7f132e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fdb0b935f80 R15: 00007ffcb3c9fe98
 </TASK>

The buggy address belongs to the variable:
 fontdata_8x16+0x1010/0x1480

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xc630
flags: 0xfff00000002000(reserved|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000002000 ffffea0000318c08 ffffea0000318c08 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffffffff8c630b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff8c630c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff8c630c80: 00 00 00 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 f9
                                                 ^
 ffffffff8c630d00: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
 ffffffff8c630d80: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
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