ghsa-vh2p-4gfm-v9v7
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
kernel: be more careful about dup_mmap() failures and uprobe registering
If a memory allocation fails during dup_mmap(), the maple tree can be left in an unsafe state for other iterators besides the exit path. All the locks are dropped before the exit_mmap() call (in mm/mmap.c), but the incomplete mm_struct can be reached through (at least) the rmap finding the vmas which have a pointer back to the mm_struct.
Up to this point, there have been no issues with being able to find an mm_struct that was only partially initialised. Syzbot was able to make the incomplete mm_struct fail with recent forking changes, so it has been proven unsafe to use the mm_struct that hasn't been initialised, as referenced in the link below.
Although 8ac662f5da19f ("fork: avoid inappropriate uprobe access to invalid mm") fixed the uprobe access, it does not completely remove the race.
This patch sets the MMF_OOM_SKIP to avoid the iteration of the vmas on the oom side (even though this is extremely unlikely to be selected as an oom victim in the race window), and sets MMF_UNSTABLE to avoid other potential users from using a partially initialised mm_struct.
When registering vmas for uprobe, skip the vmas in an mm that is marked unstable. Modifying a vma in an unstable mm may cause issues if the mm isn't fully initialised.
{
"affected": [],
"aliases": [
"CVE-2025-21709"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-27T02:15:14Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nkernel: be more careful about dup_mmap() failures and uprobe registering\n\nIf a memory allocation fails during dup_mmap(), the maple tree can be left\nin an unsafe state for other iterators besides the exit path. All the\nlocks are dropped before the exit_mmap() call (in mm/mmap.c), but the\nincomplete mm_struct can be reached through (at least) the rmap finding\nthe vmas which have a pointer back to the mm_struct.\n\nUp to this point, there have been no issues with being able to find an\nmm_struct that was only partially initialised. Syzbot was able to make\nthe incomplete mm_struct fail with recent forking changes, so it has been\nproven unsafe to use the mm_struct that hasn\u0027t been initialised, as\nreferenced in the link below.\n\nAlthough 8ac662f5da19f (\"fork: avoid inappropriate uprobe access to\ninvalid mm\") fixed the uprobe access, it does not completely remove the\nrace.\n\nThis patch sets the MMF_OOM_SKIP to avoid the iteration of the vmas on the\noom side (even though this is extremely unlikely to be selected as an oom\nvictim in the race window), and sets MMF_UNSTABLE to avoid other potential\nusers from using a partially initialised mm_struct.\n\nWhen registering vmas for uprobe, skip the vmas in an mm that is marked\nunstable. Modifying a vma in an unstable mm may cause issues if the mm\nisn\u0027t fully initialised.",
"id": "GHSA-vh2p-4gfm-v9v7",
"modified": "2025-02-27T03:34:01Z",
"published": "2025-02-27T03:34:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21709"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/64c37e134b120fb462fb4a80694bfb8e7be77b14"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/da139948aeda677ac09cc0e7d837f8a314de7d55"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
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Nomenclature
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