WARNING in iopt_map_pages (3)

Hello,

syzbot found the following issue on:

HEAD commit:    05c93f3395ed 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=14eb7c1a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3b5338ad1e59a06c
dashboard link: https://syzkaller.appspot.com/bug?extid=57fdb0cf6a0c5d1f15a2
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17dfc992580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12a926c2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6b5c913e373c/disk-05c93f33.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/15e75f1266ef/vmlinux-05c93f33.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd930129c578/Image-05c93f33.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by [email protected]

iommufd_mock iommufd_mock0: Adding to iommu group 0

------------[ cut here ]------------
WARNING: CPU: 0 PID: 6739 at drivers/iommu/iommufd/io_pagetable.c:292 iopt_alloc_area_pages drivers/iommu/iommufd/io_pagetable.c:292 [inline]
WARNING: CPU: 0 PID: 6739 at drivers/iommu/iommufd/io_pagetable.c:292 iopt_map_pages+0xd7c/0xdcc drivers/iommu/iommufd/io_pagetable.c:376
Modules linked in:
CPU: 0 UID: 0 PID: 6739 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : iopt_alloc_area_pages drivers/iommu/iommufd/io_pagetable.c:292 [inline]
pc : iopt_map_pages+0xd7c/0xdcc drivers/iommu/iommufd/io_pagetable.c:376
lr : iopt_alloc_area_pages drivers/iommu/iommufd/io_pagetable.c:292 [inline]
lr : iopt_map_pages+0xd7c/0xdcc drivers/iommu/iommufd/io_pagetable.c:376

sp : ffff8000a04f76c0
x29: ffff8000a04f78a0 x28: ffff0000d66f4810 x27: 1fffe0001acde944
x26: ffff8000a04f7b00 x25: 0000000000002fff x24: 0000000000003000
x23: ffff0000d66f4a20 x22: ffff0000d66f49f8 x21: 00000000ffffffea
x20: dfff800000000000 x19: ffff8000a04f79b0 x18: 0000000000000000
x17: ffff800083ce6110 x16: ffff80008052b3c8 x15: 0000000000000007
x14: 0000000000000000 x13: 00000000ffffffff x12: 0000000000ff0100
x11: ffff0000c72f5c40 x10: 0000000000ff0100 x9 : 0000000000000000 x8 : ffff0000c72f5c40 x7 : 0000000000000000 x6 : 000000000000003f x5 : 0000000000000040 x4 : ffffffffffffefff x3 : ffffffffffffefff x2 : 0000000000f03fff x1 : 00000000ffffffea x0 : 0000000000000000

Call trace:
  iopt_alloc_area_pages drivers/iommu/iommufd/io_pagetable.c:292 [inline] (P)
  iopt_map_pages+0xd7c/0xdcc drivers/iommu/iommufd/io_pagetable.c:376 (P)
  iopt_map_common+0x204/0x420 drivers/iommu/iommufd/io_pagetable.c:420
  iopt_map_user_pages+0xb4/0xd8 drivers/iommu/iommufd/io_pagetable.c:461
  iommufd_ioas_map+0x2d4/0x3d0 drivers/iommu/iommufd/ioas.c:276
  iommufd_fops_ioctl+0x424/0x54c drivers/iommu/iommufd/main.c:533
  vfs_ioctl fs/ioctl.c:51 [inline]
  __do_sys_ioctl fs/ioctl.c:597 [inline]
  __se_sys_ioctl fs/ioctl.c:583 [inline]
  __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583
  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
  invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49
  el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132
  do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
  el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724
  el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743

  el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
irq event stamp: 1160
hardirqs last  enabled at (1159): [<ffff80008ae21fa0>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
hardirqs last  enabled at (1159): [<ffff80008ae21fa0>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:194
hardirqs last disabled at (1160): [<ffff80008adf99f4>] el1_brk64+0x20/0x54 arch/arm64/kernel/entry-common.c:412
softirqs last  enabled at (132): [<ffff8000801f96d0>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (130): [<ffff8000801f969c>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---

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It looks to be an overflow error as user gives the below arg. But this should be expected. no?

// start: int64 = 0x1000005 (8 bytes)
// length: int64 = 0xffffffffffefffff (8 bytes)