Re: [syzbot] [usb?] BUG: unable to handle kernel paging request in xhci_halt

[syzbot <syzbot+c90273bf9017ef1462af@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: unable to handle kernel paging request in xhci_halt

xhci_hcd 0000:00:02.0: xHCI Host Controller
xhci_hcd 0000:00:02.0: new USB bus registered, assigned bus number 34
Unable to handle kernel paging request at virtual address ffff800093f3c0ff
KASAN: probably user-memory-access in range [0x000000049f9e07f8-0x000000049f9e07ff]
Mem abort info:
  ESR = 0x0000000096000021
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x21: alignment fault
Data abort info:
  ISV = 0, ISS = 0x00000021, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0
swapper pgtable: 4k pages, 48-bit VAs, pgdp=000000021b049000
[ffff800093f3c0ff] pgd=0000000000000000, p4d=1000000221341003, pud=1000000221342003, pmd=1000000108016403, pte=0068010000000713
Internal error: Oops: 0000000096000021 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 5341 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __raw_readl arch/arm64/include/asm/io.h:84 [inline]
pc : readl include/asm-generic/io.h:231 [inline]
pc : xhci_quiesce drivers/usb/host/xhci.c:107 [inline]
pc : xhci_halt+0x64/0x1ec drivers/usb/host/xhci.c:125
lr : xhci_halt+0x40/0x1ec drivers/usb/host/xhci.c:124
sp : ffff8000962f73c0
x29: ffff8000962f73c0 x28: ffff0000d6df6000 x27: dfff800000000000
x26: ffff0000d6df6418 x25: 0000000000000f01 x24: ffff0000d6df66e8
x23: ffff0000c2b100d0 x22: ffff0000d6df6418 x21: dfff800000000000
x20: 1fffe0001adbec83 x19: ffff0000d6df6400 x18: 00000000ffffffff
x17: ffff80008a7d6000 x16: 0000000000000006 x15: ffff80008a35fda0
x14: ffff80008a5d5e28 x13: 0000000000000004 x12: 0000000000000000
x11: ffff8000962f72e0 x10: 00000000fffffbf2 x9 : 7e63f6aa279c3000
x8 : ffff800093f3c0ff x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000833104ec
x2 : 0000000000000002 x1 : ffff0000c8e13a80 x0 : 0000000000000000
Call trace:
 __raw_readl arch/arm64/include/asm/io.h:84 [inline] (P)
 readl include/asm-generic/io.h:231 [inline] (P)
 xhci_quiesce drivers/usb/host/xhci.c:107 [inline] (P)
 xhci_halt+0x64/0x1ec drivers/usb/host/xhci.c:125 (P)
 xhci_gen_setup+0x5d8/0x111c drivers/usb/host/xhci.c:5496
 xhci_pci_setup+0x110/0x44c drivers/usb/host/xhci-pci.c:579
 usb_add_hcd+0x5c4/0xdec drivers/usb/core/hcd.c:2935
 usb_hcd_pci_probe+0x63c/0xaa4 drivers/usb/core/hcd-pci.c:267
 xhci_pci_common_probe+0x90/0x760 drivers/usb/host/xhci-pci.c:633
 xhci_pci_probe+0x44/0xdc drivers/usb/host/xhci-pci.c:717
 local_pci_probe+0xc8/0x158 drivers/pci/pci-driver.c:332
 pci_call_probe drivers/pci/pci-driver.c:394 [inline]
 __pci_device_probe drivers/pci/pci-driver.c:455 [inline]
 pci_device_probe+0x460/0x8d4 drivers/pci/pci-driver.c:489
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x29c/0x800 drivers/base/dd.c:706
 __driver_probe_device+0x1e0/0x350 drivers/base/dd.c:868
 device_driver_attach+0x58/0xac drivers/base/dd.c:1203
 bind_store+0xf4/0x14c drivers/base/bus.c:267
 drv_attr_store+0x80/0xa4 drivers/base/bus.c:125
 sysfs_kf_write+0xe0/0x108 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x260/0x3b8 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x51c/0xa0c fs/read_write.c:687
 ksys_write+0x12c/0x228 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __arm64_sys_write+0x84/0x98 fs/read_write.c:747
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
Code: 9762248f f94002c8 128081aa d503201f (b9400108) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	9762248f 	bl	0xfffffffffd88923c
   4:	f94002c8 	ldr	x8, [x22]
   8:	128081aa 	mov	w10, #0xfffffbf2            	// #-1038
   c:	d503201f 	nop
* 10:	b9400108 	ldr	w8, [x8] <-- trapping instruction


Tested on:

commit:         21d6ac05 Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=10fe9e79580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d1128bc53f2ef7f3
dashboard link: https://syzkaller.appspot.com/bug?extid=c90273bf9017ef1462af
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64

Note: no patches were applied.