GHSA-5V6G-VFRC-9W8P
Vulnerability from github – Published: 2024-06-25 15:31 – Updated: 2024-10-17 15:31In the Linux kernel, the following vulnerability has been resolved:
9p: add missing locking around taking dentry fid list
Fix a use-after-free on dentry's d_fsdata fid list when a thread looks up a fid through dentry while another thread unlinks it:
UAF thread: refcount_t: addition on 0; use-after-free. p9_fid_get linux/./include/net/9p/client.h:262 v9fs_fid_find+0x236/0x280 linux/fs/9p/fid.c:129 v9fs_fid_lookup_with_uid linux/fs/9p/fid.c:181 v9fs_fid_lookup+0xbf/0xc20 linux/fs/9p/fid.c:314 v9fs_vfs_getattr_dotl+0xf9/0x360 linux/fs/9p/vfs_inode_dotl.c:400 vfs_statx+0xdd/0x4d0 linux/fs/stat.c:248
Freed by: p9_fid_destroy (inlined) p9_client_clunk+0xb0/0xe0 linux/net/9p/client.c:1456 p9_fid_put linux/./include/net/9p/client.h:278 v9fs_dentry_release+0xb5/0x140 linux/fs/9p/vfs_dentry.c:55 v9fs_remove+0x38f/0x620 linux/fs/9p/vfs_inode.c:518 vfs_unlink+0x29a/0x810 linux/fs/namei.c:4335
The problem is that d_fsdata was not accessed under d_lock, because d_release() normally is only called once the dentry is otherwise no longer accessible but since we also call it explicitly in v9fs_remove that lock is required: move the hlist out of the dentry under lock then unref its fids once they are no longer accessible.
{
"affected": [],
"aliases": [
"CVE-2024-39463"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-06-25T15:15:14Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\n9p: add missing locking around taking dentry fid list\n\nFix a use-after-free on dentry\u0027s d_fsdata fid list when a thread\nlooks up a fid through dentry while another thread unlinks it:\n\nUAF thread:\nrefcount_t: addition on 0; use-after-free.\n p9_fid_get linux/./include/net/9p/client.h:262\n v9fs_fid_find+0x236/0x280 linux/fs/9p/fid.c:129\n v9fs_fid_lookup_with_uid linux/fs/9p/fid.c:181\n v9fs_fid_lookup+0xbf/0xc20 linux/fs/9p/fid.c:314\n v9fs_vfs_getattr_dotl+0xf9/0x360 linux/fs/9p/vfs_inode_dotl.c:400\n vfs_statx+0xdd/0x4d0 linux/fs/stat.c:248\n\nFreed by:\n p9_fid_destroy (inlined)\n p9_client_clunk+0xb0/0xe0 linux/net/9p/client.c:1456\n p9_fid_put linux/./include/net/9p/client.h:278\n v9fs_dentry_release+0xb5/0x140 linux/fs/9p/vfs_dentry.c:55\n v9fs_remove+0x38f/0x620 linux/fs/9p/vfs_inode.c:518\n vfs_unlink+0x29a/0x810 linux/fs/namei.c:4335\n\nThe problem is that d_fsdata was not accessed under d_lock, because\nd_release() normally is only called once the dentry is otherwise no\nlonger accessible but since we also call it explicitly in v9fs_remove\nthat lock is required:\nmove the hlist out of the dentry under lock then unref its fids once\nthey are no longer accessible.",
"id": "GHSA-5v6g-vfrc-9w8p",
"modified": "2024-10-17T15:31:07Z",
"published": "2024-06-25T15:31:09Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-39463"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3bb6763a8319170c2d41c4232c8e7e4c37dcacfb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c898afdc15645efb555acb6d85b484eb40a45409"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cb299cdba09f46f090b843d78ba26b667d50a456"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f0c5c944c6d8614c19e6e9a97fd2011dcd30e8f5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fe17ebf22feb4ad7094d597526d558a49aac92b4"
},
{
"type": "WEB",
"url": "https://www.zerodayinitiative.com/advisories/ZDI-24-1194"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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