ghsa-xjr6-8999-vr65
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
tracing: Free buffers when a used dynamic event is removed
After 65536 dynamic events have been added and removed, the "type" field of the event then uses the first type number that is available (not currently used by other events). A type number is the identifier of the binary blobs in the tracing ring buffer (known as events) to map them to logic that can parse the binary blob.
The issue is that if a dynamic event (like a kprobe event) is traced and is in the ring buffer, and then that event is removed (because it is dynamic, which means it can be created and destroyed), if another dynamic event is created that has the same number that new event's logic on parsing the binary blob will be used.
To show how this can be an issue, the following can crash the kernel:
# cd /sys/kernel/tracing
# for i in seq 65536; do
echo 'p:kprobes/foo do_sys_openat2 $arg1:u32' > kprobe_events
# done
For every iteration of the above, the writing to the kprobe_events will remove the old event and create a new one (with the same format) and increase the type number to the next available on until the type number reaches over 65535 which is the max number for the 16 bit type. After it reaches that number, the logic to allocate a new number simply looks for the next available number. When an dynamic event is removed, that number is then available to be reused by the next dynamic event created. That is, once the above reaches the max number, the number assigned to the event in that loop will remain the same.
Now that means deleting one dynamic event and created another will reuse the previous events type number. This is where bad things can happen. After the above loop finishes, the kprobes/foo event which reads the do_sys_openat2 function call's first parameter as an integer.
# echo 1 > kprobes/foo/enable # cat /etc/passwd > /dev/null # cat trace cat-2211 [005] .... 2007.849603: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849620: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849838: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849880: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 # echo 0 > kprobes/foo/enable
Now if we delete the kprobe and create a new one that reads a string:
# echo 'p:kprobes/foo do_sys_openat2 +0($arg2):string' > kprobe_events
And now we can the trace:
# cat trace sendmail-1942 [002] ..... 530.136320: foo: (do_sys_openat2+0x0/0x240) arg1= cat-2046 [004] ..... 530.930817: foo: (do_sys_openat2+0x0/0x240) arg1="������������������������������������������������������������������������������������������������" cat-2046 [004] ..... 530.930961: foo: (do_sys_openat2+0x0/0x240) arg1="������������������������������������������������������������������������������������������������" cat-2046 [004] ..... 530.934278: foo: (do_sys_openat2+0x0/0x240) arg1="������������������������������������������������������������������������������������������������" cat-2046 [004] ..... 530.934563: foo: (do_sys_openat2+0x0/0x240) arg1="��������������������������������������� ---truncated---
{
"affected": [],
"aliases": [
"CVE-2022-49006"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-21T20:15:12Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Free buffers when a used dynamic event is removed\n\nAfter 65536 dynamic events have been added and removed, the \"type\" field\nof the event then uses the first type number that is available (not\ncurrently used by other events). A type number is the identifier of the\nbinary blobs in the tracing ring buffer (known as events) to map them to\nlogic that can parse the binary blob.\n\nThe issue is that if a dynamic event (like a kprobe event) is traced and\nis in the ring buffer, and then that event is removed (because it is\ndynamic, which means it can be created and destroyed), if another dynamic\nevent is created that has the same number that new event\u0027s logic on\nparsing the binary blob will be used.\n\nTo show how this can be an issue, the following can crash the kernel:\n\n # cd /sys/kernel/tracing\n # for i in `seq 65536`; do\n echo \u0027p:kprobes/foo do_sys_openat2 $arg1:u32\u0027 \u003e kprobe_events\n # done\n\nFor every iteration of the above, the writing to the kprobe_events will\nremove the old event and create a new one (with the same format) and\nincrease the type number to the next available on until the type number\nreaches over 65535 which is the max number for the 16 bit type. After it\nreaches that number, the logic to allocate a new number simply looks for\nthe next available number. When an dynamic event is removed, that number\nis then available to be reused by the next dynamic event created. That is,\nonce the above reaches the max number, the number assigned to the event in\nthat loop will remain the same.\n\nNow that means deleting one dynamic event and created another will reuse\nthe previous events type number. This is where bad things can happen.\nAfter the above loop finishes, the kprobes/foo event which reads the\ndo_sys_openat2 function call\u0027s first parameter as an integer.\n\n # echo 1 \u003e kprobes/foo/enable\n # cat /etc/passwd \u003e /dev/null\n # cat trace\n cat-2211 [005] .... 2007.849603: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196\n cat-2211 [005] .... 2007.849620: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196\n cat-2211 [005] .... 2007.849838: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196\n cat-2211 [005] .... 2007.849880: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196\n # echo 0 \u003e kprobes/foo/enable\n\nNow if we delete the kprobe and create a new one that reads a string:\n\n # echo \u0027p:kprobes/foo do_sys_openat2 +0($arg2):string\u0027 \u003e kprobe_events\n\nAnd now we can the trace:\n\n # cat trace\n sendmail-1942 [002] ..... 530.136320: foo: (do_sys_openat2+0x0/0x240) arg1= cat-2046 [004] ..... 530.930817: foo: (do_sys_openat2+0x0/0x240) arg1=\"\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\"\n cat-2046 [004] ..... 530.930961: foo: (do_sys_openat2+0x0/0x240) arg1=\"\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\"\n cat-2046 [004] ..... 530.934278: foo: (do_sys_openat2+0x0/0x240) arg1=\"\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\"\n cat-2046 [004] ..... 530.934563: foo: (do_sys_openat2+0x0/0x240) arg1=\"\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\n---truncated---",
"id": "GHSA-xjr6-8999-vr65",
"modified": "2024-10-25T15:31:26Z",
"published": "2024-10-21T21:30:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49006"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1603feac154ff38514e8354e3079a455eb4801e2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/417d5ea6e735e5d88ffb6c436cf2938f3f476dd1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4313e5a613049dfc1819a6dfb5f94cf2caff9452"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/be111ebd8868d4b7c041cb3c6102e1ae27d6dc1d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c52d0c8c4f38f7580cff61c4dfe1034c580cedfd"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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.