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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+0x2114/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
Write of size 4 at addr ffffc90003f01fe8 by task syz.1.1097/9160

CPU: 0 PID: 9160 Comm: syz.1.1097 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:276 [inline]
 sys_imageblit+0x2114/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
 drm_fbdev_generic_defio_imageblit+0x2c/0x110 drivers/gpu/drm/drm_fbdev_generic.c:37
 cw_putcs_aligned drivers/video/fbdev/core/fbcon_cw.c:110 [inline]
 cw_putcs+0x15f3/0x18a0 drivers/video/fbdev/core/fbcon_cw.c:158
 fbcon_putcs+0x35c/0x520 drivers/video/fbdev/core/fbcon.c:1301
 do_update_region+0x4e9/0x640 drivers/tty/vt/vt.c:623
 redraw_screen+0xa30/0x1000 drivers/tty/vt/vt.c:983
 vc_do_resize+0x1256/0x17f0 drivers/tty/vt/vt.c:1291
 fbcon_do_set_font+0xb5c/0x1ae0 drivers/video/fbdev/core/fbcon.c:2440
 con_font_set drivers/tty/vt/vt.c:4629 [inline]
 con_font_op+0xc3c/0xf60 drivers/tty/vt/vt.c:4676
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:476 [inline]
 vt_ioctl+0x1a21/0x1f20 drivers/tty/vt/vt_ioctl.c:754
 tty_ioctl+0x91e/0xdc0 drivers/tty/tty_io.c:2779
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f17ffd9e159
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:00007f1800cca028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1800026090 RCX: 00007f17ffd9e159
RDX: 0000200000000180 RSI: 0000000000004b72 RDI: 0000000000000004
RBP: 00007f17ffe35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1800026128 R14: 00007f1800026090 R15: 00007fff7c77b688
 </TASK>

The buggy address belongs to a 0-page vmalloc region starting at 0xffffc90003f02000 allocated at drm_gem_shmem_vmap+0x3c4/0x650 drivers/gpu/drm/drm_gem_shmem_helper.c:340
Memory state around the buggy address:
 ffffc90003f01e80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90003f01f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90003f01f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                                          ^
 ffffc90003f02000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90003f02080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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