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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:24
Write of size 8 at addr ffffc900052f1000 by task syz.7.1109/9894

CPU: 1 UID: 0 PID: 9894 Comm: syz.7.1109 Not tainted syzkaller #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:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 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:24
 drm_fbdev_shmem_defio_fillrect+0x22/0x140 drivers/gpu/drm/drm_fbdev_shmem.c:38
 bit_clear_margins+0x2f7/0x4c0 drivers/video/fbdev/core/bitblit.c:231
 fbcon_clear_margins.constprop.0+0x1d4/0x290 drivers/video/fbdev/core/fbcon.c:1338
 fbcon_do_set_font+0x603/0x940 drivers/video/fbdev/core/fbcon.c:2470
 fbcon_set_font+0x9ed/0xb80 drivers/video/fbdev/core/fbcon.c:2570
 con_font_set drivers/tty/vt/vt.c:4887 [inline]
 con_font_op+0x7fb/0xf50 drivers/tty/vt/vt.c:4934
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
 vt_ioctl+0x48f/0x30a0 drivers/tty/vt/vt_ioctl.c:751
 tty_ioctl+0x661/0x1680 drivers/tty/tty_io.c:2792
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl fs/ioctl.c:584 [inline]
 __x64_sys_ioctl+0x18b/0x210 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f149718eba9
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:00007f1497f89038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f14973d5fa0 RCX: 00007f149718eba9
RDX: 0000200000000100 RSI: 0000000000004b72 RDI: 0000000000000003
RBP: 00007f1497211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f14973d6038 R14: 00007f14973d5fa0 R15: 00007ffdccc29ad8
 </TASK>

The buggy address belongs to a 0-page vmalloc region starting at 0xffffc90004ff1000 allocated at drm_gem_shmem_vmap_locked+0x561/0x7e0 drivers/gpu/drm/drm_gem_shmem_helper.c:371
Memory state around the buggy address:
 ffffc900052f0f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900052f0f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900052f1000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc900052f1080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc900052f1100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
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