fkie_cve-2025-38527
Vulnerability from fkie_nvd
Published
2025-08-16 12:15
Modified
2025-08-28 15:15
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix use-after-free in cifs_oplock_break
A race condition can occur in cifs_oplock_break() leading to a
use-after-free of the cinode structure when unmounting:
cifs_oplock_break()
_cifsFileInfo_put(cfile)
cifsFileInfo_put_final()
cifs_sb_deactive()
[last ref, start releasing sb]
kill_sb()
kill_anon_super()
generic_shutdown_super()
evict_inodes()
dispose_list()
evict()
destroy_inode()
call_rcu(&inode->i_rcu, i_callback)
spin_lock(&cinode->open_file_lock) <- OK
[later] i_callback()
cifs_free_inode()
kmem_cache_free(cinode)
spin_unlock(&cinode->open_file_lock) <- UAF
cifs_done_oplock_break(cinode) <- UAF
The issue occurs when umount has already released its reference to the
superblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this
releases the last reference, triggering the immediate cleanup of all
inodes under RCU. However, cifs_oplock_break() continues to access the
cinode after this point, resulting in use-after-free.
Fix this by holding an extra reference to the superblock during the
entire oplock break operation. This ensures that the superblock and
its inodes remain valid until the oplock break completes.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-after-free in cifs_oplock_break\n\nA race condition can occur in cifs_oplock_break() leading to a\nuse-after-free of the cinode structure when unmounting:\n\n cifs_oplock_break()\n _cifsFileInfo_put(cfile)\n cifsFileInfo_put_final()\n cifs_sb_deactive()\n [last ref, start releasing sb]\n kill_sb()\n kill_anon_super()\n generic_shutdown_super()\n evict_inodes()\n dispose_list()\n evict()\n destroy_inode()\n call_rcu(\u0026inode-\u003ei_rcu, i_callback)\n spin_lock(\u0026cinode-\u003eopen_file_lock) \u003c- OK\n [later] i_callback()\n cifs_free_inode()\n kmem_cache_free(cinode)\n spin_unlock(\u0026cinode-\u003eopen_file_lock) \u003c- UAF\n cifs_done_oplock_break(cinode) \u003c- UAF\n\nThe issue occurs when umount has already released its reference to the\nsuperblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this\nreleases the last reference, triggering the immediate cleanup of all\ninodes under RCU. However, cifs_oplock_break() continues to access the\ncinode after this point, resulting in use-after-free.\n\nFix this by holding an extra reference to the superblock during the\nentire oplock break operation. This ensures that the superblock and\nits inodes remain valid until the oplock break completes."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: smb: cliente: correcci\u00f3n duse after free en cifs_oplock_break. Puede producirse una condici\u00f3n de ejecuci\u00f3n en cifs_oplock_break() que provoca un use after free de la estructura cinode al desmontar: cifs_oplock_break() _cifsFileInfo_put(cfile) cifsFileInfo_put_final() cifs_sb_deactive() [\u00faltima referencia, iniciar la liberaci\u00f3n de sb] kill_sb() kill_anon_super() generic_shutdown_super() evict_inodes() dispose_list() evict() destroy_inode() call_rcu(\u0026amp;inode-\u0026gt;i_rcu, i_callback) spin_lock(\u0026amp;cinode-\u0026gt;open_file_lock) \u0026lt;- OK [m\u00e1s tarde] i_callback() cifs_free_inode() kmem_cache_free(cinode) spin_unlock(\u0026amp;cinode-\u0026gt;open_file_lock) \u0026lt;- UAF cifs_done_oplock_break(cinode) \u0026lt;- UAF El problema ocurre cuando umount ya ha liberado su referencia al superbloque. Cuando _cifsFileInfo_put() llama a cifs_sb_deactive(), se libera la \u00faltima referencia, lo que desencadena la limpieza inmediata de todos los inodos bajo RCU. Sin embargo, cifs_oplock_break() contin\u00faa accediendo al cinode despu\u00e9s de este punto, lo que resulta en un use after free. Para solucionar esto, mantenga una referencia adicional al superbloque durante toda la operaci\u00f3n de ruptura del oplock. Esto garantiza que el superbloque y sus inodos sigan siendo v\u00e1lidos hasta que se complete la ruptura del oplock."
}
],
"id": "CVE-2025-38527",
"lastModified": "2025-08-28T15:15:51.520",
"metrics": {},
"published": "2025-08-16T12:15:28.183",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/09bce2138a30ef10d8821c8c3f73a4ab7a5726bc"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/0a4eec84d4d2c4085d4ed8630fd74e4b39033c1b"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/2baaf5bbab2ac474c4f92c10fcb3310f824db995"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/4256a483fe58af66a46cbf3dc48ff26e580d3308"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/705c79101ccf9edea5a00d761491a03ced314210"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/da11bd4b697b393a207f19a2ed7d382a811a3ddc"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
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- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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