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BUG: KASAN: vmalloc-out-of-bounds in fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline]
BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x1ba8/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
Write of size 4 at addr ffffc90004901020 by task syz.5.1136/7602

CPU: 1 PID: 7602 Comm: syz.5.1136 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline]
 sys_imageblit+0x1ba8/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
 drm_fb_helper_sys_imageblit+0x2e/0x510 drivers/gpu/drm/drm_fb_helper.c:793
 soft_cursor+0x9fd/0xc30 drivers/video/fbdev/core/softcursor.c:74
 bit_cursor+0x16b5/0x1f40 drivers/video/fbdev/core/bitblit.c:409
 hide_cursor+0x7f/0x320 drivers/tty/vt/vt.c:907
 do_con_write+0x1dd/0x6c40 drivers/tty/vt/vt.c:2927
 con_put_char+0x7f/0xc0 drivers/tty/vt/vt.c:3303
 tty_put_char+0xc5/0x150 drivers/tty/tty_io.c:3178
 do_output_char+0x691/0x960 drivers/tty/n_tty.c:485
 __process_echoes+0x2a2/0x8f0 drivers/tty/n_tty.c:736
 commit_echoes drivers/tty/n_tty.c:791 [inline]
 n_tty_receive_char+0x811/0xbb0 drivers/tty/n_tty.c:1411
 n_tty_receive_buf_standard drivers/tty/n_tty.c:-1 [inline]
 __receive_buf drivers/tty/n_tty.c:1577 [inline]
 n_tty_receive_buf_common+0x170c/0x65b0 drivers/tty/n_tty.c:1674
 paste_selection+0x351/0x4e0 drivers/tty/vt/selection.c:408
 vt_ioctl+0x441/0x1ca0 drivers/tty/vt/vt_ioctl.c:764
 tty_ioctl+0x848/0xc30 drivers/tty/tty_io.c:2810
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7feefd5a0159
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:00007feefb7f8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007feefd827fa0 RCX: 00007feefd5a0159
RDX: 0000200000000000 RSI: 000000000000541c RDI: 0000000000000003
RBP: 00007feefd63703b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007feefd828038 R14: 00007feefd827fa0 R15: 00007ffe2616db38
 </TASK>


Memory state around the buggy address:
 ffffc90004900f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90004900f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90004901000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                               ^
 ffffc90004901080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90004901100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
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