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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:133 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_fillrect_static drivers/video/fbdev/core/fb_fillrect.h:219 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_fillrect drivers/video/fbdev/core/fb_fillrect.h:278 [inline]
BUG: KASAN: vmalloc-out-of-bounds in sys_fillrect+0x1da5/0x2570 drivers/video/fbdev/core/sysfillrect.c:24
Write of size 8 at addr ffffc90005f00000 by task syz.4.663/7790

CPU: 0 UID: 0 PID: 7790 Comm: syz.4.663 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline]
 bitfill drivers/video/fbdev/core/fb_fillrect.h:133 [inline]
 fb_fillrect_static drivers/video/fbdev/core/fb_fillrect.h:219 [inline]
 fb_fillrect drivers/video/fbdev/core/fb_fillrect.h:278 [inline]
 sys_fillrect+0x1da5/0x2570 drivers/video/fbdev/core/sysfillrect.c:24
 drm_fbdev_shmem_defio_fillrect+0x2c/0x110 drivers/gpu/drm/drm_fbdev_shmem.c:39
 bit_clear+0x168/0x200 drivers/video/fbdev/core/bitblit.c:72
 __fbcon_clear+0x9cd/0xd30 drivers/video/fbdev/core/fbcon.c:-1
 fbcon_scroll+0x47e/0x7c0 drivers/video/fbdev/core/fbcon.c:1927
 con_scroll+0x783/0xa10 drivers/tty/vt/vt.c:616
 csi_M drivers/tty/vt/vt.c:2191 [inline]
 csi_ECMA+0x486/0x6850 drivers/tty/vt/vt.c:2614
 do_con_trol drivers/tty/vt/vt.c:-1 [inline]
 do_con_write+0x41d8/0x5540 drivers/tty/vt/vt.c:3325
 con_put_char+0x82/0xc0 drivers/tty/vt/vt.c:3669
 tty_put_char+0xce/0x160 drivers/tty/tty_io.c:3153
 do_output_char+0x6b7/0x970 drivers/tty/n_tty.c:459
 process_output drivers/tty/n_tty.c:482 [inline]
 n_tty_write+0xdf8/0x11e0 drivers/tty/n_tty.c:2377
 iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
 file_tty_write+0x50b/0x980 drivers/tty/tty_io.c:1081
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61e/0xbb0 fs/read_write.c:687
 ksys_write+0x156/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x17b/0x530 arch/x86/entry/syscall_64.c:85
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f674350e0d9
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:00007f6741766028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6743795fa0 RCX: 00007f674350e0d9
RDX: 0000000000001006 RSI: 0000200000001980 RDI: 0000000000000007
RBP: 00007f67435a5024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6743796038 R14: 00007f6743795fa0 R15: 00007fff100973d8
 </TASK>

The buggy address belongs to a 0-page vmalloc region starting at 0xffffc90005c00000 allocated at drm_gem_shmem_vmap_locked+0x562/0x7d0 drivers/gpu/drm/drm_gem_shmem_helper.c:415
Memory state around the buggy address:
 ffffc90005efff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90005efff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90005f00000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc90005f00080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90005f00100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
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