ghsa-23g6-fhm7-588p
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
net: ipv6: ensure we call ipv6_mc_down() at most once
There are two reasons for addrconf_notify() to be called with NETDEV_DOWN: either the network device is actually going down, or IPv6 was disabled on the interface.
If either of them stays down while the other is toggled, we repeatedly call the code for NETDEV_DOWN, including ipv6_mc_down(), while never calling the corresponding ipv6_mc_up() in between. This will cause a new entry in idev->mc_tomb to be allocated for each multicast group the interface is subscribed to, which in turn leaks one struct ifmcaddr6 per nontrivial multicast group the interface is subscribed to.
The following reproducer will leak at least $n objects:
ip addr add ff2e::4242/32 dev eth0 autojoin sysctl -w net.ipv6.conf.eth0.disable_ipv6=1 for i in $(seq 1 $n); do ip link set up eth0; ip link set down eth0 done
Joining groups with IPV6_ADD_MEMBERSHIP (unprivileged) or setting the sysctl net.ipv6.conf.eth0.forwarding to 1 (=> subscribing to ff02::2) can also be used to create a nontrivial idev->mc_list, which will the leak objects with the right up-down-sequence.
Based on both sources for NETDEV_DOWN events the interface IPv6 state should be considered:
- not ready if the network interface is not ready OR IPv6 is disabled for it
- ready if the network interface is ready AND IPv6 is enabled for it
The functions ipv6_mc_up() and ipv6_down() should only be run when this state changes.
Implement this by remembering when the IPv6 state is ready, and only run ipv6_mc_down() if it actually changed from ready to not ready.
The other direction (not ready -> ready) already works correctly, as:
- the interface notification triggered codepath for NETDEV_UP / NETDEV_CHANGE returns early if ipv6 is disabled, and
- the disable_ipv6=0 triggered codepath skips fully initializing the interface as long as addrconf_link_ready(dev) returns false
- calling ipv6_mc_up() repeatedly does not leak anything
{
"affected": [],
"aliases": [
"CVE-2022-48910"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-08-22T02:15:05Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: ensure we call ipv6_mc_down() at most once\n\nThere are two reasons for addrconf_notify() to be called with NETDEV_DOWN:\neither the network device is actually going down, or IPv6 was disabled\non the interface.\n\nIf either of them stays down while the other is toggled, we repeatedly\ncall the code for NETDEV_DOWN, including ipv6_mc_down(), while never\ncalling the corresponding ipv6_mc_up() in between. This will cause a\nnew entry in idev-\u003emc_tomb to be allocated for each multicast group\nthe interface is subscribed to, which in turn leaks one struct ifmcaddr6\nper nontrivial multicast group the interface is subscribed to.\n\nThe following reproducer will leak at least $n objects:\n\nip addr add ff2e::4242/32 dev eth0 autojoin\nsysctl -w net.ipv6.conf.eth0.disable_ipv6=1\nfor i in $(seq 1 $n); do\n\tip link set up eth0; ip link set down eth0\ndone\n\nJoining groups with IPV6_ADD_MEMBERSHIP (unprivileged) or setting the\nsysctl net.ipv6.conf.eth0.forwarding to 1 (=\u003e subscribing to ff02::2)\ncan also be used to create a nontrivial idev-\u003emc_list, which will the\nleak objects with the right up-down-sequence.\n\nBased on both sources for NETDEV_DOWN events the interface IPv6 state\nshould be considered:\n\n - not ready if the network interface is not ready OR IPv6 is disabled\n for it\n - ready if the network interface is ready AND IPv6 is enabled for it\n\nThe functions ipv6_mc_up() and ipv6_down() should only be run when this\nstate changes.\n\nImplement this by remembering when the IPv6 state is ready, and only\nrun ipv6_mc_down() if it actually changed from ready to not ready.\n\nThe other direction (not ready -\u003e ready) already works correctly, as:\n\n - the interface notification triggered codepath for NETDEV_UP /\n NETDEV_CHANGE returns early if ipv6 is disabled, and\n - the disable_ipv6=0 triggered codepath skips fully initializing the\n interface as long as addrconf_link_ready(dev) returns false\n - calling ipv6_mc_up() repeatedly does not leak anything",
"id": "GHSA-23g6-fhm7-588p",
"modified": "2024-11-08T18:30:43Z",
"published": "2024-08-22T03:31:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-48910"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/24888915364cfa410de62d8abb5df95c3b67455d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/72124e65a70b84e6303a5cd21b0ac1f27d7d61a4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9588ac2eddc2f223ebcebf6e9f5caed84d32922b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9995b408f17ff8c7f11bc725c8aa225ba3a63b1c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9a8736b2da28b24f01707f592ff059b9f90a058c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b11781515208dd31fbcd0b664078dce5dc44523f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c71bf3229f9e9dd60ba02f5a5be02066edf57012"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f4c63b24dea9cc2043ff845dcca9aaf8109ea38a"
}
],
"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"
}
]
}
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