ACPI: tables: FPDT: Don't call acpi_os_map_memory() on invalid phys address
CVE: CVE-2022-50320
Component: kernel
CWE: CWE-674
Severity: Moderate
CVSS v3: 4.5/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Release date: 2022-01-01T00:00:00+00:00

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

ACPI: tables: FPDT: Don't call acpi_os_map_memory() on invalid phys address

On a Packard Bell Dot SC (Intel Atom N2600 model) there is a FPDT table
which contains invalid physical addresses, with high bits set which fall
outside the range of the CPU-s supported physical address range.

Calling acpi_os_map_memory() on such an invalid phys address leads to
the below WARN_ON in ioremap triggering resulting in an oops/stacktrace.

Add code to verify the physical address before calling acpi_os_map_memory()
to fix / avoid the oops.

[    1.226900] ioremap: invalid physical address 3001000000000000
[    1.226949] ------------[ cut here ]------------
[    1.226962] WARNING: CPU: 1 PID: 1 at arch/x86/mm/ioremap.c:200 __ioremap_caller.cold+0x43/0x5f
[    1.226996] Modules linked in:
[    1.227016] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.0.0-rc3+ #490
[    1.227029] Hardware name: Packard Bell dot s/SJE01_CT, BIOS V1.10 07/23/2013
[    1.227038] RIP: 0010:__ioremap_caller.cold+0x43/0x5f
[    1.227054] Code: 96 00 00 e9 f8 af 24 ff 89 c6 48 c7 c7 d8 0c 84 99 e8 6a 96 00 00 e9 76 af 24 ff 48 89 fe 48 c7 c7 a8 0c 84 99 e8 56 96 00 00 <0f> 0b e9 60 af 24 ff 48 8b 34 24 48 c7 c7 40 0d 84 99 e8 3f 96 00
[    1.227067] RSP: 0000:ffffb18c40033d60 EFLAGS: 00010286
[    1.227084] RAX: 0000000000000032 RBX: 3001000000000000 RCX: 0000000000000000
[    1.227095] RDX: 0000000000000001 RSI: 00000000ffffdfff RDI: 00000000ffffffff
[    1.227105] RBP: 3001000000000000 R08: 0000000000000000 R09: ffffb18c40033c18
[    1.227115] R10: 0000000000000003 R11: ffffffff99d62fe8 R12: 0000000000000008
[    1.227124] R13: 0003001000000000 R14: 0000000000001000 R15: 3001000000000000
[    1.227135] FS:  0000000000000000(0000) GS:ffff913a3c080000(0000) knlGS:0000000000000000
[    1.227146] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    1.227156] CR2: 0000000000000000 CR3: 0000000018c26000 CR4: 00000000000006e0
[    1.227167] Call Trace:
[    1.227176]  <TASK>
[    1.227185]  ? acpi_os_map_iomem+0x1c9/0x1e0
[    1.227215]  ? kmem_cache_alloc_trace+0x187/0x370
[    1.227254]  acpi_os_map_iomem+0x1c9/0x1e0
[    1.227288]  acpi_init_fpdt+0xa8/0x253
[    1.227308]  ? acpi_debugfs_init+0x1f/0x1f
[    1.227339]  do_one_initcall+0x5a/0x300
[    1.227406]  ? rcu_read_lock_sched_held+0x3f/0x80
[    1.227442]  kernel_init_freeable+0x28b/0x2cc
[    1.227512]  ? rest_init+0x170/0x170
[    1.227538]  kernel_init+0x16/0x140
[    1.227552]  ret_from_fork+0x1f/0x30
[    1.227639]  </TASK>
[    1.227647] irq event stamp: 186819
[    1.227656] hardirqs last  enabled at (186825): [<ffffffff98184a6e>] __up_console_sem+0x5e/0x70
[    1.227672] hardirqs last disabled at (186830): [<ffffffff98184a53>] __up_console_sem+0x43/0x70
[    1.227686] softirqs last  enabled at (186576): [<ffffffff980fbc9d>] __irq_exit_rcu+0xed/0x160
[    1.227701] softirqs last disabled at (186569): [<ffffffff980fbc9d>] __irq_exit_rcu+0xed/0x160
[    1.227715] ---[ end trace 0000000000000000 ]---

Statement: The bug in the ACPI FPDT parser could cause a kernel crash during boot on systems with firmware tables containing invalid physical addresses.
It cannot be exploited remotely, as the invalid values originate from BIOS/UEFI tables, making it a reliability issue rather than a security risk.
The patch ensures that only valid physical addresses are passed to acpi_os_map_memory(), preventing such boot-time crashes.

Remediation: