iommufd: Check for uptr overflow

In the Linux kernel, the following vulnerability has been resolved:

iommufd: Check for uptr overflow

syzkaller found that setting up a map with a user VA that wraps past zero
can trigger WARN_ONs, particularly from pin_user_pages weirdly returning 0
due to invalid arguments.

Prevent creating a pages with a uptr and size that would math overflow.

WARNING: CPU: 0 PID: 518 at drivers/iommu/iommufd/pages.c:793 pfn_reader_user_pin+0x2e6/0x390
Modules linked in:
CPU: 0 PID: 518 Comm: repro Not tainted 6.3.0-rc2-eeac8ede1755+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:pfn_reader_user_pin+0x2e6/0x390
Code: b1 11 e9 25 fe ff ff e8 28 e4 0f ff 31 ff 48 89 de e8 2e e6 0f ff 48 85 db 74 0a e8 14 e4 0f ff e9 4d ff ff ff e8 0a e4 0f ff <0f> 0b bb f2 ff ff ff e9 3c ff ff ff e8 f9 e3 0f ff ba 01 00 00 00
RSP: 0018:ffffc90000f9fa30 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff821e2b72
RDX: 0000000000000000 RSI: ffff888014184680 RDI: 0000000000000002
RBP: ffffc90000f9fa78 R08: 00000000000000ff R09: 0000000079de6f4e
R10: ffffc90000f9f790 R11: ffff888014185418 R12: ffffc90000f9fc60
R13: 0000000000000002 R14: ffff888007879800 R15: 0000000000000000
FS: 00007f4227555740(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000043 CR3: 000000000e748005 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<TASK>
pfn_reader_next+0x14a/0x7b0
? interval_tree_double_span_iter_update+0x11a/0x140
pfn_reader_first+0x140/0x1b0
iopt_pages_rw_slow+0x71/0x280
? __this_cpu_preempt_check+0x20/0x30
iopt_pages_rw_access+0x2b2/0x5b0
iommufd_access_rw+0x19f/0x2f0
iommufd_test+0xd11/0x16f0
? write_comp_data+0x2f/0x90
iommufd_fops_ioctl+0x206/0x330
__x64_sys_ioctl+0x10e/0x160
? __pfx_iommufd_fops_ioctl+0x10/0x10
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc