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vulnrichmentLinuxVULNRICHMENT:CVE-2024-35895
HistoryMay 19, 2024 - 8:34 a.m.

CVE-2024-35895 bpf, sockmap: Prevent lock inversion deadlock in map delete elem

2024-05-1908:34:50
Linux
github.com
1
linux kernel
vulnerability
cve-2024-35895
lock inversion
deadlock
bpf
sockmap
map delete elem

6.7 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

13.2%

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

bpf, sockmap: Prevent lock inversion deadlock in map delete elem

syzkaller started using corpuses where a BPF tracing program deletes
elements from a sockmap/sockhash map. Because BPF tracing programs can be
invoked from any interrupt context, locks taken during a map_delete_elem
operation must be hardirq-safe. Otherwise a deadlock due to lock inversion
is possible, as reported by lockdep:

   CPU0                    CPU1
   ----                    ----

lock(&htab->buckets[i].lock);
local_irq_disable();
lock(&host->lock);
lock(&htab->buckets[i].lock);
<Interrupt>
lock(&host->lock);

Locks in sockmap are hardirq-unsafe by design. We expects elements to be
deleted from sockmap/sockhash only in task (normal) context with interrupts
enabled, or in softirq context.

Detect when map_delete_elem operation is invoked from a context which is
not hardirq-unsafe, that is interrupts are disabled, and bail out with an
error.

Note that map updates are not affected by this issue. BPF verifier does not
allow updating sockmap/sockhash from a BPF tracing program today.

CNA Affected

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "604326b41a6f",
        "lessThan": "f7990498b05a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "604326b41a6f",
        "lessThan": "dd54b48db0c8",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "604326b41a6f",
        "lessThan": "d1e73fb19a4c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "604326b41a6f",
        "lessThan": "a44770fed865",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "604326b41a6f",
        "lessThan": "668b3074aa14",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "604326b41a6f",
        "lessThan": "6af057ccdd8e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "604326b41a6f",
        "lessThan": "ff9105993240",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/core/sock_map.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.20"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.20",
        "versionType": "custom"
      },
      {
        "status": "unaffected",
        "version": "5.4.274",
        "versionType": "custom",
        "lessThanOrEqual": "5.4.*"
      },
      {
        "status": "unaffected",
        "version": "5.10.215",
        "versionType": "custom",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.154",
        "versionType": "custom",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.85",
        "versionType": "custom",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.26",
        "versionType": "custom",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.8.5",
        "versionType": "custom",
        "lessThanOrEqual": "6.8.*"
      },
      {
        "status": "unaffected",
        "version": "6.9",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/core/sock_map.c"
    ],
    "defaultStatus": "affected"
  }
]

6.7 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

13.2%