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ipv6: Fix soft lockups in fib6_select_path under high next hop churn

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix soft lockups in fib6_select_path under high next hop churn Soft lockups have been observed on a cluster of Linux-based edge routers located in a highly dynamic environment. Using the `bird` service, these routers continuously update BGP-advertised routes due to frequently changing nexthop destinations, while also managing significant IPv6 traffic. The lockups occur during the traversal of the multipath circular linked-list in the `fib6_select_path` function, particularly while iterating through the siblings in the list. The issue typically arises when the nodes of the linked list are unexpectedly deleted concurrently on a different core—indicated by their 'next' and 'previous' elements pointing back to the node itself and their reference count dropping to zero. This results in an infinite loop, leading to a soft lockup that triggers a system panic via the watchdog timer. Apply RCU primitives in the problematic code sections to resolve the issue. Where necessary, update the references to fib6_siblings to annotate or use the RCU APIs. Include a test script that reproduces the issue. The script periodically updates the routing table while generating a heavy load of outgoing IPv6 traffic through multiple iperf3 clients. It consistently induces infinite soft lockups within a couple of minutes. Kernel log: 0 [ffffbd13003e8d30] machine_kexec at ffffffff8ceaf3eb 1 [ffffbd13003e8d90] __crash_kexec at fffffff

Announced Source revision 1
Original source ↗

CVE-2024-56703

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2024-56703

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83",
        "lessThan": "d0ec61c9f3583b76aebdbb271f5c0d3fcccd48b2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83",
        "lessThan": "52da02521ede55fb86546c3fffd9377b3261b91f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83",
        "lessThan": "11edcd026012ac18acee0f1514db3ed1b160fc6f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83",
        "lessThan": "34a949e7a0869dfa31a40416d2a56973fae1807b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83",
        "lessThan": "d9ccb18f83ea2bb654289b6ecf014fd267cc988b",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv6/ip6_fib.c",
      "net/ipv6/route.c",
      "tools/testing/selftests/net/Makefile",
      "tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.15"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.15",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.1.128",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.75",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.11.11",
        "versionType": "semver",
        "lessThanOrEqual": "6.11.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.2",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.13",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv6/ip6_fib.c",
      "net/ipv6/route.c",
      "tools/testing/selftests/net/Makefile",
      "tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2024-56703

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#26839 · Revision 1
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Publisher date
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