gfs2: Fix use-after-free in iomap inline data write path_CVE-2026-45984

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: Fix use-after-free in iomap inline data write path\n\nThe inline data buffer head (dibh) is being released prematurely in\ngfs2_iomap_begin() via release_metapath() while iomap->inline_data\nstill points to dibh->b_data. This causes a use-after-free when\niomap_write_end_inline() later attempts to write to the inline data\narea.\n\nThe bug sequence:\n1. gfs2_iomap_begin() calls gfs2_meta_inode_buffer() to read inode\n   metadata into dibh\n2. Sets iomap->inline_data = dibh->b_data + sizeof(struct gfs2_dinode)\n3. Calls release_metapath() which calls brelse(dibh), dropping refcount\n   to 0\n4. kswapd reclaims the page (~39ms later in the syzbot report)\n5. iomap_write_end_inline() tries to memcpy() to iomap->inline_data\n6. KASAN detects use-after-free write to freed memory\n\nFix by storing dibh in iomap->private and incrementing its refcount\nwith get_bh() in gfs2_iomap_begin(). The buffer is then properly\nreleased in gfs2_iomap_end() after the inline write completes,\nensuring the page stays alive for the entire iomap operation.\n\nNote: A C reproducer is not available for this issue. The fix is based\non analysis of the KASAN report and code review showing the buffer head\nis freed before use.\n\n[agruenba: Take buffer head reference in gfs2_iomap_begin() to avoid\nleaks in gfs2_iomap_get() and gfs2_iomap_alloc().]",
    "published": "2026-05-27T12:18:42.964Z",
    "modified": "2026-05-30T10:46:25.407Z",
    "type": "cve",
    "title": "gfs2: Fix use-after-free in iomap inline data write path",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/1403989d1b502f4a2c0d0b42ccf1c25748442eff\nhttps://git.kernel.org/stable/c/1cae1bafdf9caa9b462b19af06b1a06902e4e142\nhttps://git.kernel.org/stable/c/764c3c84b5683e608f43735c803a5f415046686c\nhttps://git.kernel.org/stable/c/d87268326b277af3665237ac76a73dd9fa8e21b4\nhttps://git.kernel.org/stable/c/87d4954b5c59735a99ea98cb208d47130f6dce7d\nhttps://git.kernel.org/stable/c/6d76febba07c40bcf358f63216d36ea68cf1c215\nhttps://git.kernel.org/stable/c/815ddd27c0c7171a99fe802fdb19098ddef8b19d\nhttps://git.kernel.org/stable/c/faddeb848305e79db89ee0479bb0e33380656321",
    "id": "CVE-2026-45984",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux d0a22a4b03b8475b7aa3fa41243c26c291407844\nLinux Linux d0a22a4b03b8475b7aa3fa41243c26c291407844\nLinux Linux d0a22a4b03b8475b7aa3fa41243c26c291407844\nLinux Linux d0a22a4b03b8475b7aa3fa41243c26c291407844\nLinux Linux d0a22a4b03b8475b7aa3fa41243c26c291407844\nLinux Linux d0a22a4b03b8475b7aa3fa41243c26c291407844\nLinux Linux d0a22a4b03b8475b7aa3fa41243c26c291407844\nLinux Linux d0a22a4b03b8475b7aa3fa41243c26c291407844\nLinux Linux 5.2",
    "sourceHref": "",
    "cvss": {
        "score": 7.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
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        "baseScore": 0,
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        "confidentialityImpact": "",
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    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "d0a22a4b03b8475b7aa3fa41243c26c291407844",
    "vendor": "Linux",
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}