ghsa-gpxm-mp2h-x3pp
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
net: Make tcp_allowed_congestion_control readonly in non-init netns
Currently, tcp_allowed_congestion_control is global and writable; writing to it in any net namespace will leak into all other net namespaces.
tcp_available_congestion_control and tcp_allowed_congestion_control are the only sysctls in ipv4_net_table (the per-netns sysctl table) with a NULL data pointer; their handlers (proc_tcp_available_congestion_control and proc_allowed_congestion_control) have no other way of referencing a struct net. Thus, they operate globally.
Because ipv4_net_table does not use designated initializers, there is no easy way to fix up this one "bad" table entry. However, the data pointer updating logic shouldn't be applied to NULL pointers anyway, so we instead force these entries to be read-only.
These sysctls used to exist in ipv4_table (init-net only), but they were moved to the per-net ipv4_net_table, presumably without realizing that tcp_allowed_congestion_control was writable and thus introduced a leak.
Because the intent of that commit was only to know (i.e. read) "which congestion algorithms are available or allowed", this read-only solution should be sufficient.
The logic added in recent commit 31c4d2f160eb: ("net: Ensure net namespace isolation of sysctls") does not and cannot check for NULL data pointers, because other table entries (e.g. /proc/sys/net/netfilter/nf_log/) have .data=NULL but use other methods (.extra2) to access the struct net.
{
"affected": [],
"aliases": [
"CVE-2021-46912"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-02-27T07:15:07Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: Make tcp_allowed_congestion_control readonly in non-init netns\n\nCurrently, tcp_allowed_congestion_control is global and writable;\nwriting to it in any net namespace will leak into all other net\nnamespaces.\n\ntcp_available_congestion_control and tcp_allowed_congestion_control are\nthe only sysctls in ipv4_net_table (the per-netns sysctl table) with a\nNULL data pointer; their handlers (proc_tcp_available_congestion_control\nand proc_allowed_congestion_control) have no other way of referencing a\nstruct net. Thus, they operate globally.\n\nBecause ipv4_net_table does not use designated initializers, there is no\neasy way to fix up this one \"bad\" table entry. However, the data pointer\nupdating logic shouldn\u0027t be applied to NULL pointers anyway, so we\ninstead force these entries to be read-only.\n\nThese sysctls used to exist in ipv4_table (init-net only), but they were\nmoved to the per-net ipv4_net_table, presumably without realizing that\ntcp_allowed_congestion_control was writable and thus introduced a leak.\n\nBecause the intent of that commit was only to know (i.e. read) \"which\ncongestion algorithms are available or allowed\", this read-only solution\nshould be sufficient.\n\nThe logic added in recent commit\n31c4d2f160eb: (\"net: Ensure net namespace isolation of sysctls\")\ndoes not and cannot check for NULL data pointers, because\nother table entries (e.g. /proc/sys/net/netfilter/nf_log/) have\n.data=NULL but use other methods (.extra2) to access the struct net.",
"id": "GHSA-gpxm-mp2h-x3pp",
"modified": "2024-04-17T18:31:31Z",
"published": "2024-02-27T09:31:16Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-46912"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1ccdf1bed140820240e383ba0accc474ffc7f006"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/35d7491e2f77ce480097cabcaf93ed409e916e12"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/97684f0970f6e112926de631fdd98d9693c7e5c1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.