CVE-2021-47243

2024-05-2115:15:13

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

web.nvd.nist.gov

linux kernel

vulnerability

sch_cake

tcp options

parsing

out of bounds

fix

nvd

6.7 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.6%

JSON

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

sch_cake: Fix out of bounds when parsing TCP options and header

The TCP option parser in cake qdisc (cake_get_tcpopt and
cake_tcph_may_drop) could read one byte out of bounds. When the length
is 1, the execution flow gets into the loop, reads one byte of the
opcode, and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, it reads
one more byte, which exceeds the length of 1.

This fix is inspired by commit 9609dad263f8 (“ipv4: tcp_input: fix stack
out of bounds when parsing TCP options.”).

v2 changes:

Added doff validation in cake_get_tcphdr to avoid parsing garbage as TCP
header. Although it wasn’t strictly an out-of-bounds access (memory was
allocated), garbage values could be read where CAKE expected the TCP
header if doff was smaller than 5.

Affected configurations

Vulners

Node

linuxlinux_kernelRange4.19–4.19.196

linuxlinux_kernelRange4.20.0–5.4.128

linuxlinux_kernelRange5.5.0–5.10.46

linuxlinux_kernelRange5.11.0–5.12.13

linuxlinux_kernelRange5.13.0≥

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/sched/sch_cake.c"
    ],
    "versions": [
      {
        "version": "8b7138814f29",
        "lessThan": "595897ef118d",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "8b7138814f29",
        "lessThan": "4cefa061fc63",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "8b7138814f29",
        "lessThan": "3b491dd593d5",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "8b7138814f29",
        "lessThan": "3371392c60e2",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "8b7138814f29",
        "lessThan": "ba91c49dedbd",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/sched/sch_cake.c"
    ],
    "versions": [
      {
        "version": "4.19",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "4.19",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.196",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.128",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.46",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.12.13",
        "lessThanOrEqual": "5.12.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.13",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]