{"id":"AZL-47844","summary":"CVE-2024-39463 affecting package kernel for versions less than 5.15.176.3-1","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's 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.","modified":"2026-04-01T05:15:58.591629Z","published":"2024-06-25T15:15:14Z","upstream":["CVE-2024-39463"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-39463"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:2","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.176.3-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-47844.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}