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BUG: KASAN: vmalloc-out-of-bounds in fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline]
BUG: KASAN: vmalloc-out-of-bounds in bitfill drivers/video/fbdev/core/fb_fillrect.h:134 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_fillrect_static drivers/video/fbdev/core/fb_fillrect.h:220 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_fillrect drivers/video/fbdev/core/fb_fillrect.h:279 [inline]
BUG: KASAN: vmalloc-out-of-bounds in sys_fillrect+0x15d4/0x17b0 drivers/video/fbdev/core/sysfillrect.c:22
Write of size 8 at addr ffffc90005301000 by task syz.3.1003/9290

CPU: 0 UID: 0 PID: 9290 Comm: syz.3.1003 Not tainted 6.16.0-rc4-syzkaller-00013-g66701750d556 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xcd/0x680 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline]
 bitfill drivers/video/fbdev/core/fb_fillrect.h:134 [inline]
 fb_fillrect_static drivers/video/fbdev/core/fb_fillrect.h:220 [inline]
 fb_fillrect drivers/video/fbdev/core/fb_fillrect.h:279 [inline]
 sys_fillrect+0x15d4/0x17b0 drivers/video/fbdev/core/sysfillrect.c:22
 drm_fbdev_shmem_defio_fillrect+0x22/0x140 drivers/gpu/drm/drm_fbdev_shmem.c:37
 bit_clear_margins+0x2f4/0x4c0 drivers/video/fbdev/core/bitblit.c:231
 fbcon_clear_margins.constprop.0+0x1d0/0x290 drivers/video/fbdev/core/fbcon.c:1325
 fbcon_switch+0xa01/0x14c0 drivers/video/fbdev/core/fbcon.c:2196
 redraw_screen+0x2be/0x760 drivers/tty/vt/vt.c:965
 fbcon_set_disp+0x7d4/0xe40 drivers/video/fbdev/core/fbcon.c:1418
 con2fb_init_display drivers/video/fbdev/core/fbcon.c:816 [inline]
 set_con2fb_map+0x703/0x1060 drivers/video/fbdev/core/fbcon.c:889
 fbcon_set_con2fb_map_ioctl+0x16c/0x220 drivers/video/fbdev/core/fbcon.c:3118
 do_fb_ioctl+0x328/0x7e0 drivers/video/fbdev/core/fb_chrdev.c:138
 fb_ioctl+0xe5/0x150 drivers/video/fbdev/core/fb_chrdev.c:169
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __x64_sys_ioctl+0x18b/0x210 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc2e878e929
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:00007fc2e9686038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc2e89b5fa0 RCX: 00007fc2e878e929
RDX: 0000200000000180 RSI: 0000000000004610 RDI: 0000000000000006
RBP: 00007fc2e8810b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc2e89b5fa0 R15: 00007ffd5df0ee78
 </TASK>

The buggy address belongs to the virtual mapping at
 [ffffc90005001000, ffffc90005302000) created by:
 drm_gem_shmem_vmap_locked+0x4bc/0x720 drivers/gpu/drm/drm_gem_shmem_helper.c:369

Memory state around the buggy address:
 ffffc90005300f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90005300f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90005301000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc90005301080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90005301100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
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