7.8

CVE-2024-39463

In 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.
Data is provided by the National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version >= 5.11 < 6.1.94
Linux ≫ Linux Kernel Version >= 6.2 < 6.6.34
Linux ≫ Linux Kernel Version >= 6.7 < 6.9.5
Linux ≫ Linux Kernel Version6.10 Updaterc1
Zu dieser CVE wurde keine CISA KEV oder CERT.AT-Warnung gefunden.
EPSS Metriken
Type Source Score Percentile
EPSS FIRST.org 0.02% 0.049
CVSS Metriken
Source Base Score Exploit Score Impact Score Vector string
nvd@nist.gov 7.8 1.8 5.9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
134c704f-9b21-4f2e-91b3-4a467353bcc0 7.8 1.8 5.9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE-416 Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.