ghsa-9fq4-227m-74p5
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
secretmem: disable memfd_secret() if arch cannot set direct map
Return -ENOSYS from memfd_secret() syscall if !can_set_direct_map(). This is the case for example on some arm64 configurations, where marking 4k PTEs in the direct map not present can only be done if the direct map is set up at 4k granularity in the first place (as ARM's break-before-make semantics do not easily allow breaking apart large/gigantic pages).
More precisely, on arm64 systems with !can_set_direct_map(), set_direct_map_invalid_noflush() is a no-op, however it returns success (0) instead of an error. This means that memfd_secret will seemingly "work" (e.g. syscall succeeds, you can mmap the fd and fault in pages), but it does not actually achieve its goal of removing its memory from the direct map.
Note that with this patch, memfd_secret() will start erroring on systems where can_set_direct_map() returns false (arm64 with CONFIG_RODATA_FULL_DEFAULT_ENABLED=n, CONFIG_DEBUG_PAGEALLOC=n and CONFIG_KFENCE=n), but that still seems better than the current silent failure. Since CONFIG_RODATA_FULL_DEFAULT_ENABLED defaults to 'y', most arm64 systems actually have a working memfd_secret() and aren't be affected.
From going through the iterations of the original memfd_secret patch series, it seems that disabling the syscall in these scenarios was the intended behavior 1 (preferred over having set_direct_map_invalid_noflush return an error as that would result in SIGBUSes at page-fault time), however the check for it got dropped between v16 2 and v17 3, when secretmem moved away from CMA allocations.
{
"affected": [],
"aliases": [
"CVE-2024-50182"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-11-08T06:15:15Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsecretmem: disable memfd_secret() if arch cannot set direct map\n\nReturn -ENOSYS from memfd_secret() syscall if !can_set_direct_map(). This\nis the case for example on some arm64 configurations, where marking 4k\nPTEs in the direct map not present can only be done if the direct map is\nset up at 4k granularity in the first place (as ARM\u0027s break-before-make\nsemantics do not easily allow breaking apart large/gigantic pages).\n\nMore precisely, on arm64 systems with !can_set_direct_map(),\nset_direct_map_invalid_noflush() is a no-op, however it returns success\n(0) instead of an error. This means that memfd_secret will seemingly\n\"work\" (e.g. syscall succeeds, you can mmap the fd and fault in pages),\nbut it does not actually achieve its goal of removing its memory from the\ndirect map.\n\nNote that with this patch, memfd_secret() will start erroring on systems\nwhere can_set_direct_map() returns false (arm64 with\nCONFIG_RODATA_FULL_DEFAULT_ENABLED=n, CONFIG_DEBUG_PAGEALLOC=n and\nCONFIG_KFENCE=n), but that still seems better than the current silent\nfailure. Since CONFIG_RODATA_FULL_DEFAULT_ENABLED defaults to \u0027y\u0027, most\narm64 systems actually have a working memfd_secret() and aren\u0027t be\naffected.\n\nFrom going through the iterations of the original memfd_secret patch\nseries, it seems that disabling the syscall in these scenarios was the\nintended behavior [1] (preferred over having\nset_direct_map_invalid_noflush return an error as that would result in\nSIGBUSes at page-fault time), however the check for it got dropped between\nv16 [2] and v17 [3], when secretmem moved away from CMA allocations.\n\n[1]: https://lore.kernel.org/lkml/20201124164930.GK8537@kernel.org/\n[2]: https://lore.kernel.org/lkml/20210121122723.3446-11-rppt@kernel.org/#t\n[3]: https://lore.kernel.org/lkml/20201125092208.12544-10-rppt@kernel.org/",
"id": "GHSA-9fq4-227m-74p5",
"modified": "2024-11-29T21:31:01Z",
"published": "2024-11-08T06:30:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-50182"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/532b53cebe58f34ce1c0f34d866f5c0e335c53c6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5ea0b7af38754d2b45ead9257bca47e84662e926"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/757786abe4547eb3d9d0e8350a63bdb0f9824af2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7caf966390e6e4ebf42775df54e7ee1f280ce677"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d0ae6ffa1aeb297aef89f49cfb894a83c329ebad"
}
],
"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.