---
id: CVE-2024-26706
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  parisc: Fix random data corruption from exception handler

  The current exception handler implementation, which assists when accessing
  user space memory, may exhibit ran…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  parisc: Fix random data corruption from exception handler

  The current exception handler implementation, which assists when accessing
  user space memory, may exhibit ran…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-787
vendor: linux
product: linux_kernel
affected:
  - linux_kernel < 6.1.79
  - 'linux_kernel >= 6.2, < 6.6.18'
  - 'linux_kernel >= 6.7, < 6.7.6'
  - linux_kernel = 6.8
patched:
  - linux_kernel 6.7.6
published: '2024-04-03'
updated: '2026-08-04'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2024-26706'
references:
  - url: 'https://git.kernel.org/stable/c/23027309b099ffc4efca5477009a11dccbdae592'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8b1d72395635af45410b66cc4c4ab37a12c4a831'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ce31d79aa1f13a2345791f84935281a2c194e003'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fa69a8063f8b27f3c7434a0d4f464a76a62f24d2'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/23027309b099ffc4efca5477009a11dccbdae592'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/8b1d72395635af45410b66cc4c4ab37a12c4a831'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/ce31d79aa1f13a2345791f84935281a2c194e003'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/fa69a8063f8b27f3c7434a0d4f464a76a62f24d2'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00263
epssPercentile: 0.16145
ingestedAt: '2026-08-05T10:46:48.142Z'
---

## Overview

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

parisc: Fix random data corruption from exception handler

The current exception handler implementation, which assists when accessing
user space memory, may exhibit random data corruption if the compiler decides
to use a different register than the specified register %r29 (defined in
ASM_EXCEPTIONTABLE_REG) for the error code. If the compiler choose another
register, the fault handler will nevertheless store -EFAULT into %r29 and thus
trash whatever this register is used for.
Looking at the assembly I found that this happens sometimes in emulate_ldd().

To solve the issue, the easiest solution would be if it somehow is
possible to tell the fault handler which register is used to hold the error
code. Using %0 or %1 in the inline assembly is not posssible as it will show
up as e.g. %r29 (with the "%r" prefix), which the GNU assembler can not
convert to an integer.

This patch takes another, better and more flexible approach:
We extend the __ex_table (which is out of the execution path) by one 32-word.
In this word we tell the compiler to insert the assembler instruction
"or %r0,%r0,%reg", where %reg references the register which the compiler
choosed for the error return code.
In case of an access failure, the fault handler finds the __ex_table entry and
can examine the opcode. The used register is encoded in the lowest 5 bits, and
the fault handler can then store -EFAULT into this register.

Since we extend the __ex_table to 3 words we can't use the BUILDTIME_TABLE_SORT
config option any longer.

## Affected

- `linux_kernel < 6.1.79`
- `linux_kernel >= 6.2, < 6.6.18`
- `linux_kernel >= 6.7, < 6.7.6`
- `linux_kernel = 6.8`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.7.6`