CVE-2021-47428

2024-05-2115:15:28

416baaa9-dc9f-4396-8d5f-8c081fb06d67

web.nvd.nist.gov

linux kernel

vulnerability

emergency stack

powerpc

program check

interrupt

6.6 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.5%

JSON

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

powerpc/64s: fix program check interrupt emergency stack path

Emergency stack path was jumping into a 3: label inside the
__GEN_COMMON_BODY macro for the normal path after it had finished,
rather than jumping over it. By a small miracle this is the correct
place to build up a new interrupt frame with the existing stack
pointer, so things basically worked okay with an added weird looking
700 trap frame on top (which had the wrong ->nip so it didn’t decode
bug messages either).

Fix this by avoiding using numeric labels when jumping over non-trivial
macros.

Before:

LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
Modules linked in:
CPU: 0 PID: 88 Comm: sh Not tainted 5.15.0-rc2-00034-ge057cdade6e5 #2637
NIP: 7265677368657265 LR: c00000000006c0c8 CTR: c0000000000097f0
REGS: c0000000fffb3a50 TRAP: 0700 Not tainted
MSR: 9000000000021031 <SF,HV,ME,IR,DR,LE> CR: 00000700 XER: 20040000
CFAR: c0000000000098b0 IRQMASK: 0
GPR00: c00000000006c964 c0000000fffb3cf0 c000000001513800 0000000000000000
GPR04: 0000000048ab0778 0000000042000000 0000000000000000 0000000000001299
GPR08: 000001e447c718ec 0000000022424282 0000000000002710 c00000000006bee8
GPR12: 9000000000009033 c0000000016b0000 00000000000000b0 0000000000000001
GPR16: 0000000000000000 0000000000000002 0000000000000000 0000000000000ff8
GPR20: 0000000000001fff 0000000000000007 0000000000000080 00007fff89d90158
GPR24: 0000000002000000 0000000002000000 0000000000000255 0000000000000300
GPR28: c000000001270000 0000000042000000 0000000048ab0778 c000000080647e80
NIP [7265677368657265] 0x7265677368657265
LR [c00000000006c0c8] ___do_page_fault+0x3f8/0xb10
Call Trace:
[c0000000fffb3cf0] [c00000000000bdac] soft_nmi_common+0x13c/0x1d0 (unreliable)
— interrupt: 700 at decrementer_common_virt+0xb8/0x230
NIP: c0000000000098b8 LR: c00000000006c0c8 CTR: c0000000000097f0
REGS: c0000000fffb3d60 TRAP: 0700 Not tainted
MSR: 9000000000021031 <SF,HV,ME,IR,DR,LE> CR: 22424282 XER: 20040000
CFAR: c0000000000098b0 IRQMASK: 0
GPR00: c00000000006c964 0000000000002400 c000000001513800 0000000000000000
GPR04: 0000000048ab0778 0000000042000000 0000000000000000 0000000000001299
GPR08: 000001e447c718ec 0000000022424282 0000000000002710 c00000000006bee8
GPR12: 9000000000009033 c0000000016b0000 00000000000000b0 0000000000000001
GPR16: 0000000000000000 0000000000000002 0000000000000000 0000000000000ff8
GPR20: 0000000000001fff 0000000000000007 0000000000000080 00007fff89d90158
GPR24: 0000000002000000 0000000002000000 0000000000000255 0000000000000300
GPR28: c000000001270000 0000000042000000 0000000048ab0778 c000000080647e80
NIP [c0000000000098b8] decrementer_common_virt+0xb8/0x230
LR [c00000000006c0c8] ___do_page_fault+0x3f8/0xb10
— interrupt: 700
Instruction dump:
XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
—[ end trace 6d28218e0cc3c949 ]—

After:

------------[ cut here ]------------
kernel BUG at arch/powerpc/kernel/exceptions-64s.S:491!
Oops: Exception in kernel mode, sig: 5 [#1]
LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
Modules linked in:
CPU: 0 PID: 88 Comm: login Not tainted 5.15.0-rc2-00034-ge057cdade6e5-dirty #2638
NIP: c0000000000098b8 LR: c00000000006bf04 CTR: c0000000000097f0
REGS: c0000000fffb3d60 TRAP: 0700 Not tainted
MSR: 9000000000021031 <SF,HV,ME,IR,DR,LE> CR: 24482227 XER: 00040000
CFAR: c0000000000098b0 IRQMASK: 0
GPR00: c00000000006bf04 0000000000002400 c000000001513800 c000000001271868
GPR04: 00000000100f0d29 0000000042000000 0000000000000007 0000000000000009
GPR08: 00000000100f0d29 0000000024482227 0000000000002710 c000000000181b3c
GPR12: 9000000000009033 c0000000016b0000 00000000100f0d29 c000000005b22f00
GPR16: 00000000ffff0000 0000000000000001 0000000000000009 00000000100eed90
GPR20: 00000000100eed90 00000
—truncated—

Affected configurations

Vulners

Node

linuxlinux_kernelRange5.3–5.10.73

linuxlinux_kernelRange5.11.0–5.14.12

linuxlinux_kernelRange5.15.0≥

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/powerpc/kernel/exceptions-64s.S"
    ],
    "versions": [
      {
        "version": "0a882e28468f",
        "lessThan": "411b38fe68ba",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "0a882e28468f",
        "lessThan": "c835b3d1d636",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "0a882e28468f",
        "lessThan": "3e607dc4df18",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/powerpc/kernel/exceptions-64s.S"
    ],
    "versions": [
      {
        "version": "5.3",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.3",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.73",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.14.12",
        "lessThanOrEqual": "5.14.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]