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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 ffffc90024596240 by task syz.0.1588/10616

CPU: 1 UID: 0 PID: 10616 Comm: syz.0.1588 Not tainted syzkaller #0 PREEMPT(full) 
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
 ud_putcs_unaligned drivers/video/fbdev/core/fbcon_ud.c:146 [inline]
 ud_putcs+0x922/0xdf0 drivers/video/fbdev/core/fbcon_ud.c:203
 fbcon_putcs+0x3b2/0x480 drivers/video/fbdev/core/fbcon.c:1399
 do_update_region+0x2cf/0x3f0 drivers/tty/vt/vt.c:656
 invert_screen+0x27c/0x590 drivers/tty/vt/vt.c:777
 highlight drivers/tty/vt/selection.c:57 [inline]
 clear_selection drivers/tty/vt/selection.c:87 [inline]
 clear_selection+0x59/0x70 drivers/tty/vt/selection.c:83
 fbcon_modechanged+0x15a/0x7f0 drivers/video/fbdev/core/fbcon.c:2659
 fbcon_update_vcs+0x47/0x60 drivers/video/fbdev/core/fbcon.c:2741
 fb_set_var_from_user drivers/video/fbdev/core/fbmem.c:359 [inline]
 fb_set_var_from_user+0xa7/0xc0 drivers/video/fbdev/core/fbmem.c:352
 do_fb_ioctl+0x1f3/0x730 drivers/video/fbdev/core/fb_chrdev.c:88
 fb_compat_ioctl+0x4f5/0x680 drivers/video/fbdev/core/fb_chrdev.c:287
 __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
 __ia32_compat_sys_ioctl+0x2cf/0x360 fs/ioctl.c:638
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
 __do_fast_syscall_32+0x13a/0x8b0 arch/x86/entry/syscall_32.c:291
 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf701efec
Code: Unable to access opcode bytes at 0xf701efc2.
RSP: 002b:00000000f540d50c EFLAGS: 00000292 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000004601
RDX: 0000000080000040 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
Memory state around the buggy address:
 ffffc90024596100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90024596180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90024596200: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                           ^
 ffffc90024596280: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90024596300: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
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