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BUG: KASAN: vmalloc-out-of-bounds in fast_imageblit drivers/video/fbdev/core/sysimgblt.c:276 [inline]
BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x2110/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
Write of size 4 at addr ffffc900044c9ff8 by task syz.6.2167/13661

CPU: 1 PID: 13661 Comm: syz.6.2167 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:276 [inline]
 sys_imageblit+0x2110/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
 drm_fb_helper_sys_imageblit+0x2e/0x510 drivers/gpu/drm/drm_fb_helper.c:864
 cw_putcs_aligned drivers/video/fbdev/core/fbcon_cw.c:110 [inline]
 cw_putcs+0x15ef/0x18a0 drivers/video/fbdev/core/fbcon_cw.c:158
 fbcon_putcs+0x358/0x510 drivers/video/fbdev/core/fbcon.c:1300
 do_update_region+0x4e5/0x640 drivers/tty/vt/vt.c:676
 redraw_screen+0xa2c/0x1000 drivers/tty/vt/vt.c:1035
 vc_do_resize+0x122c/0x17b0 drivers/tty/vt/vt.c:1342
 fbcon_do_set_font+0xb5c/0x1ae0 drivers/video/fbdev/core/fbcon.c:2446
 con_font_set drivers/tty/vt/vt.c:4678 [inline]
 con_font_op+0xac1/0xdb0 drivers/tty/vt/vt.c:4724
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
 vt_ioctl+0x1635/0x1cc0 drivers/tty/vt/vt_ioctl.c:752
 tty_ioctl+0x7e6/0xba0 drivers/tty/tty_io.c:2776
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f664099e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6641902028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6640c26180 RCX: 00007f664099e0d9
RDX: 00002000000001c0 RSI: 0000000000004b72 RDI: 0000000000000006
RBP: 00007f6640a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6640c26218 R14: 00007f6640c26180 R15: 00007ffcf64d2158
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
Memory state around the buggy address:
 ffffc900044c9e80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc900044c9f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc900044c9f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                                                ^
 ffffc900044ca000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc900044ca080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
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