CVE-2024-35995

In the Linux kernel, the following vulnerability has been resolved: ACPI:
CPPC: Use access_width over bit_width for system memory accesses To align
with ACPI 6.3+, since bit_width can be any 8-bit value, it cannot be
depended on to be always on a clean 8b boundary. This was uncovered on the
Cobalt 100 platform. SError Interrupt on CPU26, code 0xbe000011 – SError
CPU: 26 PID: 1510 Comm: systemd-udevd Not tainted 5.15.2.1-13 #1 Hardware
name: MICROSOFT CORPORATION, BIOS MICROSOFT CORPORATION pstate: 62400009
(nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=–) pc :
cppc_get_perf_caps+0xec/0x410 lr : cppc_get_perf_caps+0xe8/0x410 sp :
ffff8000155ab730 x29: ffff8000155ab730 x28: ffff0080139d0038 x27:
ffff0080139d0078 x26: 0000000000000000 x25: ffff0080139d0058 x24:
00000000ffffffff x23: ffff0080139d0298 x22: ffff0080139d0278 x21:
0000000000000000 x20: ffff00802b251910 x19: ffff0080139d0000 x18:
ffffffffffffffff x17: 0000000000000000 x16: ffffdc7e111bad04 x15:
ffff00802b251008 x14: ffffffffffffffff x13: ffff013f1fd63300 x12:
0000000000000006 x11: ffffdc7e128f4420 x10: 0000000000000000 x9 :
ffffdc7e111badec x8 : ffff00802b251980 x7 : 0000000000000000 x6 :
ffff0080139d0028 x5 : 0000000000000000 x4 : ffff0080139d0018 x3 :
00000000ffffffff x2 : 0000000000000008 x1 : ffff8000155ab7a0 x0 :
0000000000000000 Kernel panic - not syncing: Asynchronous SError Interrupt
CPU: 26 PID: 1510 Comm: systemd-udevd Not tainted 5.15.2.1-13 #1 Hardware
name: MICROSOFT CORPORATION, BIOS MICROSOFT CORPORATION Call trace:
dump_backtrace+0x0/0x1e0 show_stack+0x24/0x30 dump_stack_lvl+0x8c/0xb8
dump_stack+0x18/0x34 panic+0x16c/0x384 add_taint+0x0/0xc0
arm64_serror_panic+0x7c/0x90 arm64_is_fatal_ras_serror+0x34/0xa4
do_serror+0x50/0x6c el1h_64_error_handler+0x40/0x74 el1h_64_error+0x7c/0x80
cppc_get_perf_caps+0xec/0x410 cppc_cpufreq_cpu_init+0x74/0x400
[cppc_cpufreq] cpufreq_online+0x2dc/0xa30 cpufreq_add_dev+0xc0/0xd4
subsys_interface_register+0x134/0x14c cpufreq_register_driver+0x1b0/0x354
cppc_cpufreq_init+0x1a8/0x1000 [cppc_cpufreq] do_one_initcall+0x50/0x250
do_init_module+0x60/0x27c load_module+0x2300/0x2570
__do_sys_finit_module+0xa8/0x114 __arm64_sys_finit_module+0x2c/0x3c
invoke_syscall+0x78/0x100 el0_svc_common.constprop.0+0x180/0x1a0
do_el0_svc+0x84/0xa0 el0_svc+0x2c/0xc0 el0t_64_sync_handler+0xa4/0x12c
el0t_64_sync+0x1a4/0x1a8 Instead, use access_width to determine the size
and use the offset and width to shift and mask the bits to read/write out.
Make sure to add a check for system memory since pcc redefines the
access_width to subspace id. If access_width is not set, then fall back to
using bit_width. [ rjw: Subject and changelog edits, comment adjustments ]