GHSA-X88W-2PQ9-75R8
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-17 18:31In the Linux kernel, the following vulnerability has been resolved:
md/md-llbitmap: prevent create failure bitmap UAF
llbitmap_create() publishes mddev->bitmap before reading the bitmap superblock. This is needed because llbitmap_read_sb() can initialize a new bitmap and flush it through helpers that use mddev->bitmap.
If llbitmap_read_sb() fails, the old cleanup dropped bitmap_info.mutex and freed llbitmap before clearing mddev->bitmap. Readers such as /proc/mdstat rely on bitmap_info.mutex to keep the bitmap pointer stable while collecting bitmap stats, so they could observe the stale pointer after the failed create path released the mutex.
Clear mddev->bitmap while still holding bitmap_info.mutex, then free the failed llbitmap after dropping the mutex. This makes mutex-protected readers see either a live bitmap or no bitmap.
{
"affected": [],
"aliases": [
"CVE-2026-90277"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:24Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd/md-llbitmap: prevent create failure bitmap UAF\n\nllbitmap_create() publishes mddev-\u003ebitmap before reading the bitmap\nsuperblock. This is needed because llbitmap_read_sb() can initialize a\nnew bitmap and flush it through helpers that use mddev-\u003ebitmap.\n\nIf llbitmap_read_sb() fails, the old cleanup dropped bitmap_info.mutex\nand freed llbitmap before clearing mddev-\u003ebitmap. Readers such as\n/proc/mdstat rely on bitmap_info.mutex to keep the bitmap pointer stable\nwhile collecting bitmap stats, so they could observe the stale pointer\nafter the failed create path released the mutex.\n\nClear mddev-\u003ebitmap while still holding bitmap_info.mutex, then free the\nfailed llbitmap after dropping the mutex. This makes mutex-protected\nreaders see either a live bitmap or no bitmap.",
"id": "GHSA-x88w-2pq9-75r8",
"modified": "2026-09-17T18:31:58Z",
"published": "2026-09-17T18:31:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90277"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2116c2f0a0e547615886900e2ed8c529c016499b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2f0722435ce3a844dbb66b9bb0a18229dcc8739c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/930cc4f1af5a1afcd545a6ba00e38921ff8401e0"
}
],
"schema_version": "1.4.0",
"severity": []
}
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