UBUNTU-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.
02 / AFFECTED SOFTWARE
Affected packages
7 explicit affected versions
4 explicit affected versions
33 explicit affected versions
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49 explicit affected versions
10 explicit affected versions
3 explicit affected versions
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54 explicit affected versions
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6 explicit affected versions
35 explicit affected versions
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64 explicit affected versions
9 explicit affected versions
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7 explicit affected versions
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12 explicit affected versions
14 explicit affected versions
7 explicit affected versions
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37 explicit affected versions
26 explicit affected versions
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10 explicit affected versions
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60 explicit affected versions
3 explicit affected versions
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57 explicit affected versions
19 explicit affected versions
33 explicit affected versions
23 explicit affected versions
10 explicit affected versions
1 explicit affected versions
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7 explicit affected versions
12 explicit affected versions
46 explicit affected versions
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10 explicit affected versions
26 explicit affected versions
11 explicit affected versions
1 explicit affected versions
3 explicit affected versions
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13 explicit affected versions
11 explicit affected versions
16 explicit affected versions
59 explicit affected versions
12 explicit affected versions
47 explicit affected versions
2 explicit affected versions
51 explicit affected versions
9 explicit affected versions
12 explicit affected versions
45 explicit affected versions
5 explicit affected versions
27 explicit affected versions
31 explicit affected versions
5 explicit affected versions
8 explicit affected versions
20 explicit affected versions
8 explicit affected versions
13 explicit affected versions
13 explicit affected versions
7 explicit affected versions
50 explicit affected versions
26 explicit affected versions
12 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
45 explicit affected versions
37 explicit affected versions
12 explicit affected versions
14 explicit affected versions
38 explicit affected versions
49 explicit affected versions
9 explicit affected versions
48 explicit affected versions
11 explicit affected versions
56 explicit affected versions
7 explicit affected versions
29 explicit affected versions
4 explicit affected versions
1 explicit affected versions
1 explicit affected versions
54 explicit affected versions
13 explicit affected versions
43 explicit affected versions
10 explicit affected versions
8 explicit affected versions
14 explicit affected versions
4 explicit affected versions
11 explicit affected versions
1 explicit affected versions
5 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/c898afdc15645efb555acb6d85b484eb40a45409
- https://git.kernel.org/stable/c/c898afdc15645efb555acb6d85b484eb40a45409
- https://git.kernel.org/stable/c/cb299cdba09f46f090b843d78ba26b667d50a456
- https://git.kernel.org/stable/c/f0c5c944c6d8614c19e6e9a97fd2011dcd30e8f5
- https://git.kernel.org/stable/c/fe17ebf22feb4ad7094d597526d558a49aac92b4
- https://ubuntu.com/security/CVE-2024-39463
- https://ubuntu.com/security/notices/USN-6999-1
- https://ubuntu.com/security/notices/USN-6999-2
- https://ubuntu.com/security/notices/USN-7004-1
- https://ubuntu.com/security/notices/USN-7005-1
- https://ubuntu.com/security/notices/USN-7005-2
- https://ubuntu.com/security/notices/USN-7008-1
- https://ubuntu.com/security/notices/USN-7029-1
- https://ubuntu.com/security/notices/USN-7166-1
- https://ubuntu.com/security/notices/USN-7166-2
- https://ubuntu.com/security/notices/USN-7166-3
- https://ubuntu.com/security/notices/USN-7166-4
- https://ubuntu.com/security/notices/USN-7186-1
- https://ubuntu.com/security/notices/USN-7186-2
- https://ubuntu.com/security/notices/USN-7194-1
- https://www.cve.org/CVERecord?id=CVE-2024-39463