CVE-2024-26768 (Low severity, published 2024-04-02)
CVSS score: 4.4 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-121
Description: In the Linux kernel, the following vulnerability has been resolved:

LoongArch: Change acpi_core_pic[NR_CPUS] to acpi_core_pic[MAX_CORE_PIC]

With default config, the value of NR_CPUS is 64. When HW platform has
more then 64 cpus, system will crash on these platforms. MAX_CORE_PIC
is the maximum cpu number in MADT table (max physical number) which can
exceed the supported maximum cpu number (NR_CPUS, max logical number),
but kernel should not crash. Kernel should boot cpus with NR_CPUS, let
the remainder cpus stay in BIOS.

The potential crash reason is that the array acpi_core_pic[NR_CPUS] can
be overflowed when parsing MADT table, and it is obvious that CORE_PIC
should be corresponding to physical core rather than logical core, so it
is better to define the array as acpi_core_pic[MAX_CORE_PIC].

With the patch, system can boot up 64 vcpus with qemu parameter -smp 128,
otherwise system will crash with the following message.

[    0.000000] CPU 0 Unable to handle kernel paging request at virtual address 0000420000004259, era == 90000000037a5f0c, ra == 90000000037a46ec
[    0.000000] Oops[#1]:
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 6.8.0-rc2+ #192
[    0.000000] Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 2/2/2022
[    0.000000] pc 90000000037a5f0c ra 90000000037a46ec tp 9000000003c90000 sp 9000000003c93d60
[    0.000000] a0 0000000000000019 a1 9000000003d93bc0 a2 0000000000000000 a3 9000000003c93bd8
[    0.000000] a4 9000000003c93a74 a5 9000000083c93a67 a6 9000000003c938f0 a7 0000000000000005
[    0.000000] t0 0000420000004201 t1 0000000000000000 t2 0000000000000001 t3 0000000000000001
[    0.000000] t4 0000000000000003 t5 0000000000000000 t6 0000000000000030 t7 0000000000000063
[    0.000000] t8 0000000000000014 u0 ffffffffffffffff s9 0000000000000000 s0 9000000003caee98
[    0.000000] s1 90000000041b0480 s2 9000000003c93da0 s3 9000000003c93d98 s4 9000000003c93d90
[    0.000000] s5 9000000003caa000 s6 000000000a7fd000 s7 000000000f556b60 s8 000000000e0a4330
[    0.000000]    ra: 90000000037a46ec platform_init+0x214/0x250
[    0.000000]   ERA: 90000000037a5f0c efi_runtime_init+0x30/0x94
[    0.000000]  CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE)
[    0.000000]  PRMD: 00000000 (PPLV0 -PIE -PWE)
[    0.000000]  EUEN: 00000000 (-FPE -SXE -ASXE -BTE)
[    0.000000]  ECFG: 00070800 (LIE=11 VS=7)
[    0.000000] ESTAT: 00010000 [PIL] (IS= ECode=1 EsubCode=0)
[    0.000000]  BADV: 0000420000004259
[    0.000000]  PRID: 0014c010 (Loongson-64bit, Loongson-3A5000)
[    0.000000] Modules linked in:
[    0.000000] Process swapper (pid: 0, threadinfo=(____ptrval____), task=(____ptrval____))
[    0.000000] Stack : 9000000003c93a14 9000000003800898 90000000041844f8 90000000037a46ec
[    0.000000]         000000000a7fd000 0000000008290000 0000000000000000 0000000000000000
[    0.000000]         0000000000000000 0000000000000000 00000000019d8000 000000000f556b60
[    0.000000]         000000000a7fd000 000000000f556b08 9000000003ca7700 9000000003800000
[    0.000000]         9000000003c93e50 9000000003800898 9000000003800108 90000000037a484c
[    0.000000]         000000000e0a4330 000000000f556b60 000000000a7fd000 000000000f556b08
[    0.000000]         9000000003ca7700 9000000004184000 0000000000200000 000000000e02b018
[    0.000000]         000000000a7fd000 90000000037a0790 9000000003800108 0000000000000000
[    0.000000]         0000000000000000 000000000e0a4330 000000000f556b60 000000000a7fd000
[    0.000000]         000000000f556b08 000000000eaae298 000000000eaa5040 0000000000200000
[    0.000000]         ...
[    0.000000] Call Trace:
[    0.000000] [<90000000037a5f0c>] efi_runtime_init+0x30/0x94
[    0.000000] [<90000000037a46ec>] platform_init+0x214/0x250
[    0.000000] [<90000000037a484c>] setup_arch+0x124/0x45c
[    0.000000] [<90000000037a0790>] start_kernel+0x90/0x670
[    0.000000] [<900000000378b0d8>] kernel_entry+0xd8/0xdc