GHSA-QP86-W2FG-H37H
Vulnerability from github – Published: 2025-05-01 15:31 – Updated: 2025-11-07 18:30In the Linux kernel, the following vulnerability has been resolved:
dm ioctl: fix misbehavior if list_versions races with module loading
__list_versions will first estimate the required space using the "dm_target_iterate(list_version_get_needed, &needed)" call and then will fill the space using the "dm_target_iterate(list_version_get_info, &iter_info)" call. Each of these calls locks the targets using the "down_read(&_lock)" and "up_read(&_lock)" calls, however between the first and second "dm_target_iterate" there is no lock held and the target modules can be loaded at this point, so the second "dm_target_iterate" call may need more space than what was the first "dm_target_iterate" returned.
The code tries to handle this overflow (see the beginning of list_version_get_info), however this handling is incorrect.
The code sets "param->data_size = param->data_start + needed" and "iter_info.end = (char *)vers+len" - "needed" is the size returned by the first dm_target_iterate call; "len" is the size of the buffer allocated by userspace.
"len" may be greater than "needed"; in this case, the code will write up to "len" bytes into the buffer, however param->data_size is set to "needed", so it may write data past the param->data_size value. The ioctl interface copies only up to param->data_size into userspace, thus part of the result will be truncated.
Fix this bug by setting "iter_info.end = (char *)vers + needed;" - this guarantees that the second "dm_target_iterate" call will write only up to the "needed" buffer and it will exit with "DM_BUFFER_FULL_FLAG" if it overflows the "needed" space - in this case, userspace will allocate a larger buffer and retry.
Note that there is also a bug in list_version_get_needed - we need to add "strlen(tt->name) + 1" to the needed size, not "strlen(tt->name)".
{
"affected": [],
"aliases": [
"CVE-2022-49771"
],
"database_specific": {
"cwe_ids": [
"CWE-362"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-01T15:16:00Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm ioctl: fix misbehavior if list_versions races with module loading\n\n__list_versions will first estimate the required space using the\n\"dm_target_iterate(list_version_get_needed, \u0026needed)\" call and then will\nfill the space using the \"dm_target_iterate(list_version_get_info,\n\u0026iter_info)\" call. Each of these calls locks the targets using the\n\"down_read(\u0026_lock)\" and \"up_read(\u0026_lock)\" calls, however between the first\nand second \"dm_target_iterate\" there is no lock held and the target\nmodules can be loaded at this point, so the second \"dm_target_iterate\"\ncall may need more space than what was the first \"dm_target_iterate\"\nreturned.\n\nThe code tries to handle this overflow (see the beginning of\nlist_version_get_info), however this handling is incorrect.\n\nThe code sets \"param-\u003edata_size = param-\u003edata_start + needed\" and\n\"iter_info.end = (char *)vers+len\" - \"needed\" is the size returned by the\nfirst dm_target_iterate call; \"len\" is the size of the buffer allocated by\nuserspace.\n\n\"len\" may be greater than \"needed\"; in this case, the code will write up\nto \"len\" bytes into the buffer, however param-\u003edata_size is set to\n\"needed\", so it may write data past the param-\u003edata_size value. The ioctl\ninterface copies only up to param-\u003edata_size into userspace, thus part of\nthe result will be truncated.\n\nFix this bug by setting \"iter_info.end = (char *)vers + needed;\" - this\nguarantees that the second \"dm_target_iterate\" call will write only up to\nthe \"needed\" buffer and it will exit with \"DM_BUFFER_FULL_FLAG\" if it\noverflows the \"needed\" space - in this case, userspace will allocate a\nlarger buffer and retry.\n\nNote that there is also a bug in list_version_get_needed - we need to add\n\"strlen(tt-\u003ename) + 1\" to the needed size, not \"strlen(tt-\u003ename)\".",
"id": "GHSA-qp86-w2fg-h37h",
"modified": "2025-11-07T18:30:25Z",
"published": "2025-05-01T15:31:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49771"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0c8d4112df329bf3dfbf27693f918c3b08676538"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3a1c35d72dc0b34d1e746ed705790c0f630aa427"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4fe1ec995483737f3d2a14c3fe1d8fe634972979"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5398b8e275bf81a2517b327d216c0f37ac9ac5ae"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6a818db0d5aecf80d4ba9e10ac153f60adc629ca"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6ffce7a92ef5c68f7e5d6f4d722c2f96280c064b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b545c0e1e4094d4de2bdfe9a3823f9154b0c0005"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f59f5a269ca5e43c567aca7f1f52500a0186e9b7"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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