BUG: unable to handle kernel paging request in fb_videomode_to

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	general protection fault in fb_videomode_to_var fbdev				1	9d04h	5d03h	0/28	moderation: reported on 2024/12/16 08:12
Unable to handle kernel paging request at virtual address dfff800000000001
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
Mem abort info:
  ESR = 0x0000000096000005
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x05: level 1 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[dfff800000000001] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 8009 Comm: syz.1.327 Not tainted 6.10.0-rc7-syzkaller-gc912bf709078 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : fb_videomode_to_var+0x3c/0x638 drivers/video/fbdev/core/modedb.c:905
lr : fb_videomode_to_var+0x2c/0x638 drivers/video/fbdev/core/modedb.c:904
sp : ffff800099797320
x29: ffff800099797330 x28: ffff800093d19160 x27: 0000000000000020
x26: 0000000000000001 x25: ffff800093d191d0 x24: ffff800099797400
x23: 1ffff000127a3223 x22: ffff800093d19020 x21: dfff800000000000
x20: 0000000000000000 x19: ffff800099797400 x18: ffff800099796e40
x17: 0000000000000000 x16: ffff80008af004c0 x15: 0000000000000004
x14: 0000000000000000 x13: ffff7000132f2e94 x12: 0000000000000000
x11: 0000000000040000 x10: 0000000000000007 x9 : 0000000000000001
x8 : 000000000000000c x7 : 0000000000000000 x6 : 000000000000003f
x5 : 0000000000000040 x4 : 0000000000000000 x3 : 0000000000000020
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff800099797400
Call trace:
 fb_videomode_to_var+0x3c/0x638 drivers/video/fbdev/core/modedb.c:905
 display_to_var drivers/video/fbdev/core/fbcon.c:904 [inline]
 fbcon_switch+0x67c/0x1c08 drivers/video/fbdev/core/fbcon.c:2097
 redraw_screen+0x514/0xd48 drivers/tty/vt/vt.c:957
 vc_do_resize+0xcd8/0x11c8 drivers/tty/vt/vt.c:1272
 __vc_resize+0x5c/0x70 drivers/tty/vt/vt.c:1294
 vc_resize include/linux/vt_kern.h:49 [inline]
 fbcon_modechanged+0x6d0/0x1094 drivers/video/fbdev/core/fbcon.c:2659
 fbcon_set_all_vcs+0xc34/0xc6c drivers/video/fbdev/core/fbcon.c:2706
 fbcon_update_vcs+0x2c/0x4c drivers/video/fbdev/core/fbcon.c:2713
 do_fb_ioctl+0x7d0/0x8bc drivers/video/fbdev/core/fb_chrdev.c:92
 fb_ioctl+0xec/0x134 drivers/video/fbdev/core/fb_chrdev.c:169
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:893
 __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:131
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:150
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
Code: 91003288 d343fd09 1200090a 11000d4a (38f56929) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	91003288 	add	x8, x20, #0xc
   4:	d343fd09 	lsr	x9, x8, #3
   8:	1200090a 	and	w10, w8, #0x7
   c:	11000d4a 	add	w10, w10, #0x3
* 10:	38f56929 	ldrsb	w9, [x9, x21] <-- trapping instruction