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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 fb_bitmap_2ppw drivers/video/fbdev/core/fb_imageblit.h:364 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_bitmap_imageblit drivers/video/fbdev/core/fb_imageblit.h:462 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_imageblit drivers/video/fbdev/core/fb_imageblit.h:492 [inline]
BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x1a6f/0x1e60 drivers/video/fbdev/core/sysimgblt.c:22
Write of size 8 at addr ffffc90003989be0 by task syz.3.1111/8798

CPU: 0 UID: 0 PID: 8798 Comm: syz.3.1111 Tainted: G          I         6.15.0-rc5-syzkaller-00300-g3ce9925823c7 #0 PREEMPT(full) 
Tainted: [I]=FIRMWARE_WORKAROUND
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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+0xc3/0x670 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]
 fb_bitmap_2ppw drivers/video/fbdev/core/fb_imageblit.h:364 [inline]
 fb_bitmap_imageblit drivers/video/fbdev/core/fb_imageblit.h:462 [inline]
 fb_imageblit drivers/video/fbdev/core/fb_imageblit.h:492 [inline]
 sys_imageblit+0x1a6f/0x1e60 drivers/video/fbdev/core/sysimgblt.c:22
 drm_fbdev_shmem_defio_imageblit+0x20/0x130 drivers/gpu/drm/drm_fbdev_shmem.c:37
 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:138 [inline]
 bit_putcs+0x90f/0xde0 drivers/video/fbdev/core/bitblit.c:187
 fbcon_putcs+0x380/0x4a0 drivers/video/fbdev/core/fbcon.c:1309
 do_update_region+0x2e6/0x3f0 drivers/tty/vt/vt.c:619
 invert_screen+0x1e4/0x590 drivers/tty/vt/vt.c:740
 highlight drivers/tty/vt/selection.c:57 [inline]
 vc_do_selection drivers/tty/vt/selection.c:331 [inline]
 vc_selection drivers/tty/vt/selection.c:373 [inline]
 set_selection_kernel+0xd23/0x14a0 drivers/tty/vt/selection.c:382
 set_selection_user+0xe8/0x140 drivers/tty/vt/selection.c:208
 tioclinux+0x36d/0x5d0 drivers/tty/vt/vt.c:3348
 vt_ioctl+0x2e8f/0x2f50 drivers/tty/vt/vt_ioctl.c:761
 tty_ioctl+0x65a/0x1610 drivers/tty/tty_io.c:2802
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f88f2f8e969
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:00007f88f3e27038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f88f31b5fa0 RCX: 00007f88f2f8e969
RDX: 0000000000000000 RSI: 000000000000541c RDI: 0000000000000001
RBP: 00007f88f3010ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f88f31b5fa0 R15: 00007ffd0dd578f8
 </TASK>

The buggy address ffffc90003989be0 belongs to a vmalloc virtual mapping
Memory state around the buggy address:
 ffffc90003989a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90003989b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90003989b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                                       ^
 ffffc90003989c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90003989c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
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