syzbot


BUG: unable to handle kernel paging request in fb_videomode_to_var

Status: upstream: reported C repro on 2025/04/29 08:31
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+5f0d5cd0f34d4276a2eb@syzkaller.appspotmail.com
First crash: 10d, last: 10d
Bug presence (1)
Date Name Commit Repro Result
2025/04/30 upstream (ToT) 8bac8898fe39 C [report] BUG: unable to handle kernel paging request in fb_videomode_to_var
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: unable to handle kernel paging request in fb_videomode_to_var fbdev 1 300d 296d 0/28 auto-obsoleted due to no activity on 2024/10/11 19:33
upstream general protection fault in fb_videomode_to_var fbdev 4 5d15h 144d 0/28 moderation: reported on 2024/12/16 08:12

Sample crash report:
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
Unable to handle kernel paging request at virtual address dfff800000000001
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
[dfff800000000001] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4023 Comm: syz-executor326 Not tainted 5.15.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : fb_videomode_to_var+0x3c/0x638 drivers/video/fbdev/core/modedb.c:901
lr : fb_videomode_to_var+0x2c/0x638 drivers/video/fbdev/core/modedb.c:900
sp : ffff80001f297420
x29: ffff80001f297430 x28: ffff70000282a1c0 x27: 00000000000000f8
x26: ffff0000cb04b000 x25: ffff0000cb07c5a0 x24: ffff80001f2974e0
x23: ffff800014150e00 x22: 0000000000000000 x21: dfff800000000000
x20: 0000000000000000 x19: ffff80001f2974e0 x18: 0000000000000000
x17: 0000000000000000 x16: ffff80000acbd360 x15: 0000000000000004
x14: 0000000000ff0100 x13: 0000000000000000 x12: 0000000000ff0100
x11: 0000000000000000 x10: 0000000000000007 x9 : 0000000000000001
x8 : 000000000000000c x7 : 0000000000000000 x6 : 000000000000003f
x5 : 0000000000000040 x4 : ffffffffffffffe0 x3 : 0000000000000080
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff80001f2974e0
Call trace:
 fb_videomode_to_var+0x3c/0x638 drivers/video/fbdev/core/modedb.c:901
 display_to_var drivers/video/fbdev/core/fbcon.c:921 [inline]
 fbcon_switch+0x458/0x19ac drivers/video/fbdev/core/fbcon.c:2111
 redraw_screen+0x4c0/0xcb8 drivers/tty/vt/vt.c:1021
 vc_do_resize+0xc2c/0x10e0 drivers/tty/vt/vt.c:1342
 vc_resize+0x54/0x68 drivers/tty/vt/vt.c:1362
 fbcon_modechanged+0x5ac/0xe4c drivers/video/fbdev/core/fbcon.c:2708
 fbcon_update_vcs+0x3c/0x4c drivers/video/fbdev/core/fbcon.c:2764
 do_fb_ioctl+0xaf0/0xcb0 drivers/video/fbdev/core/fbmem.c:1130
 fb_ioctl+0xec/0x134 drivers/video/fbdev/core/fbmem.c:1205
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
Code: 91003288 d343fd09 1200090a 11000d4a (38f56929) 
---[ end trace a8d45f90bbd014fb ]---
----------------
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

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/29 10:54 linux-5.15.y f7347f400572 aeb6ec69 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 BUG: unable to handle kernel paging request in fb_videomode_to_var
2025/04/29 08:30 linux-5.15.y f7347f400572 aeb6ec69 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 BUG: unable to handle kernel paging request in fb_videomode_to_var
* Struck through repros no longer work on HEAD.