==================================================================
BUG: KASAN: vmalloc-out-of-bounds in fb_read_offset drivers/video/fbdev/core/sysmem.h:38 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_bitblit drivers/video/fbdev/core/fb_imageblit.h:137 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_bitmap1x_imageblit drivers/video/fbdev/core/fb_imageblit.h:275 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_bitmap_imageblit drivers/video/fbdev/core/fb_imageblit.h:477 [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+0x1bd6/0x1d60 drivers/video/fbdev/core/sysimgblt.c:24
Read of size 8 at addr ffffc900053b9370 by task syz.1.876/10311

CPU: 2 UID: 0 PID: 10311 Comm: syz.1.876 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
 fb_read_offset drivers/video/fbdev/core/sysmem.h:38 [inline]
 fb_bitblit drivers/video/fbdev/core/fb_imageblit.h:137 [inline]
 fb_bitmap1x_imageblit drivers/video/fbdev/core/fb_imageblit.h:275 [inline]
 fb_bitmap_imageblit drivers/video/fbdev/core/fb_imageblit.h:477 [inline]
 fb_imageblit drivers/video/fbdev/core/fb_imageblit.h:492 [inline]
 sys_imageblit+0x1bd6/0x1d60 drivers/video/fbdev/core/sysimgblt.c:24
 drm_fbdev_shmem_defio_imageblit+0x20/0x130 drivers/gpu/drm/drm_fbdev_shmem.c:39
 soft_cursor+0x524/0xa10 drivers/video/fbdev/core/softcursor.c:74
 bit_cursor+0xcf1/0x14d0 drivers/video/fbdev/core/bitblit.c:372
 fbcon_cursor+0x43c/0x5e0 drivers/video/fbdev/core/fbcon.c:1410
 hide_cursor+0x87/0x230 drivers/tty/vt/vt.c:997
 do_con_write+0x220c/0x4ae0 drivers/tty/vt/vt.c:3418
 con_put_char+0x73/0xa0 drivers/tty/vt/vt.c:3786
 tty_put_char+0xbe/0x160 drivers/tty/tty_io.c:3144
 __process_echoes+0x11e/0xb10 drivers/tty/n_tty.c:704
 flush_echoes drivers/tty/n_tty.c:785 [inline]
 __receive_buf drivers/tty/n_tty.c:1618 [inline]
 n_tty_receive_buf_common+0x462/0x1930 drivers/tty/n_tty.c:1715
 tty_ldisc_receive_buf+0xaa/0x1a0 drivers/tty/tty_buffer.c:394
 paste_selection+0x4ca/0x790 drivers/tty/vt/selection.c:439
 tioclinux+0x5a7/0x640 drivers/tty/vt/vt.c:3699
 vt_ioctl+0x145d/0x3170 drivers/tty/vt/vt_ioctl.c:757
 tty_ioctl+0x26a/0x1870 drivers/tty/tty_io.c:2782
 vfs_ioctl fs/ioctl.c:52 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl fs/ioctl.c:584 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x7b0 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7f43da94d9
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:00007f7f44c21028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7f44025fa0 RCX: 00007f7f43da94d9
RDX: 0000200000001840 RSI: 000000000000541c RDI: 0000000000000008
RBP: 00007f7f43e3804e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7f44026038 R14: 00007f7f44025fa0 R15: 00007ffd490f7418
 </TASK>

The buggy address belongs to a 0-page vmalloc region starting at 0xffffc90004fd1000 allocated at drm_gem_shmem_vmap_locked+0x553/0x860 drivers/gpu/drm/drm_gem_shmem_helper.c:415
Memory state around the buggy address:
 ffffc900053b9200: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc900053b9280: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc900053b9300: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                                             ^
 ffffc900053b9380: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc900053b9400: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================