CVE-2026-46052
Estado: ModificadaAlta (7.5)—
In the Linux kernel, the following vulnerability has been resolved:
ceph: only d_add() negative dentries when they are unhashed
Ceph can call d_add(dentry, NULL) on a negative dentry that is already present in the primary dcache hash.
In the current VFS that is not safe. d_add() goes through __d_add() to __d_rehash(), which unconditionally reinserts dentry->d_hash into the hlist_bl bucket. If the dentry is already hashed, reinserting the same node can corrupt the bucket, including creating a self-loop. Once that happens, __d_lookup() can spin forever in the hlist_bl walk, typically looping only on the d_name.hash mismatch check and eventually triggering RCU stall reports like this one:
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This is reachable with reused cached negative dentries. A Ceph lookup or atomic_open can be handed a negative dentry that is already hashed, and fs/ceph/dir.c then hits one of two paths that incorrectly assume "negative" also means "unhashed":
Both paths can therefore re-add an already-hashed negative dentry.
Ceph already uses the correct pattern elsewhere: ceph_fill_trace() only calls d_add(dn, NULL) for a negative null-dentry reply when d_unhashed(dn) is true.
Fix both fs/ceph/dir.c sites the same way: only call d_add() for a negative dentry when it is actually unhashed. If the negative dentry is already hashed, leave it in place and reuse it as-is.
This preserves the existing behavior for unhashed dentries while avoiding d_hash list corruption for reused hashed negatives.
Detalles técnicos trazas, registros y código del informe original
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 87-....: (2100 ticks this GP) idle=3a4c/1/0x4000000000000000 softirq=25003319/25003319 fqs=829
rcu: (t=2101 jiffies g=79058445 q=698988 ncpus=192)
CPU: 87 UID: 2952868916 PID: 3933303 Comm: php-cgi8.3 Not tainted 6.18.17-i1-amd #950 NONE
Hardware name: Dell Inc. PowerEdge R7615/0G9DHV, BIOS 1.6.6 09/22/2023
RIP: 0010:__d_lookup+0x46/0xb0
Code: c1 e8 07 48 8d 04 c2 48 8b 00 49 89 fc 49 89 f5 48 89 c3 48 83 e3 fe 48 83 f8 01 77 0f eb 2d 0f 1f 44 00 00 48 8b 1b 48 85 db <74> 20 39 6b 18 75 f3 48 8d 7b 78 e8 ba 85 d0 00 4c 39 63 10 74 1f
RSP: 0018:ff745a70c8253898 EFLAGS: 00000282
RAX: ff26e470054cb208 RBX: ff26e470054cb208 RCX: 000000006e958966
RDX: ff26e48267340000 RSI: ff745a70c82539b0 RDI: ff26e458f74655c0
RBP: 000000006e958966 R08: 0000000000000180 R09: 9cd08d909b919a89
R10: ff26e458f74655c0 R11: 0000000000000000 R12: ff26e458f74655c0
R13: ff745a70c82539b0 R14: d0d0d0d0d0d0d0d0 R15: 2f2f2f2f2f2f2f2f
FS: 00007f5770896980(0000) GS:ff26e482c5d88000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5764de50c0 CR3: 000000a72abb5001 CR4: 0000000000771ef0
PKRU: 55555554
Call Trace:
<TASK>
lookup_fast+0x9f/0x100
walk_component+0x1f/0x150
link_path_walk+0x20e/0x3d0
path_lookupat+0x68/0x180
filename_lookup+0xdc/0x1e0
vfs_statx+0x6c/0x140
vfs_fstatat+0x67/0xa0
__do_sys_newfstatat+0x24/0x60
do_syscall_64+0x6a/0x230
entry_SYSCALL_64_after_hwframe+0x76/0x7e
- ceph_finish_lookup():
MDS reply is -ENOENT with no trace
-> d_add(dentry, NULL)
- ceph_lookup():
local ENOENT fast path for a complete directory with shared caps
-> d_add(dentry, NULL)CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 7.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.72%
- Percentil entre todas las CVEs puntuadas: 52
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access60 % - Impacto principal
T1499Endpoint Denial of Serviceimpact55 %
Inferido por reglas deterministas a partir del vector CVSS y la CWE. Solo orientativo.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
CWE
- NVD-CWE-noinfo
Referencias
- https://git.kernel.org/stable/c/2010cb06b9df7d3c816c78358c566bdacbdf38ff
- https://git.kernel.org/stable/c/4147ae08824cc8b65d2b2018f79d416af2937108
- https://git.kernel.org/stable/c/4179cc390dacebc87079419ec92f86f3dc46294d
- https://git.kernel.org/stable/c/73b47a1f06dee5e61b00dee5227d75d3f1f6d977
- https://git.kernel.org/stable/c/79ffcbeac6bc1dc1bcdb0434acf250f6215ec111
- https://git.kernel.org/stable/c/803447f93d75ab6e40c85e6d12b5630d281d70d6
- https://git.kernel.org/stable/c/83ce43a21bb7df8dd52228afdd918d2d058eefde
- https://git.kernel.org/stable/c/b91e535f208c48a5e7464f1aa38338a30e7912df
JSON original (NVD)
Mostrar
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"descriptions": [
{
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: only d_add() negative dentries when they are unhashed\n\nCeph can call d_add(dentry, NULL) on a negative dentry that is already\npresent in the primary dcache hash.\n\nIn the current VFS that is not safe. d_add() goes through __d_add()\nto __d_rehash(), which unconditionally reinserts dentry->d_hash into\nthe hlist_bl bucket. If the dentry is already hashed, reinserting the\nsame node can corrupt the bucket, including creating a self-loop.\nOnce that happens, __d_lookup() can spin forever in the hlist_bl walk,\ntypically looping only on the d_name.hash mismatch check and\neventually triggering RCU stall reports like this one:\n\n rcu: INFO: rcu_sched self-detected stall on CPU\n rcu: 87-....: (2100 ticks this GP) idle=3a4c/1/0x4000000000000000 softirq=25003319/25003319 fqs=829\n rcu: (t=2101 jiffies g=79058445 q=698988 ncpus=192)\n CPU: 87 UID: 2952868916 PID: 3933303 Comm: php-cgi8.3 Not tainted 6.18.17-i1-amd #950 NONE\n Hardware name: Dell Inc. PowerEdge R7615/0G9DHV, BIOS 1.6.6 09/22/2023\n RIP: 0010:__d_lookup+0x46/0xb0\n Code: c1 e8 07 48 8d 04 c2 48 8b 00 49 89 fc 49 89 f5 48 89 c3 48 83 e3 fe 48 83 f8 01 77 0f eb 2d 0f 1f 44 00 00 48 8b 1b 48 85 db <74> 20 39 6b 18 75 f3 48 8d 7b 78 e8 ba 85 d0 00 4c 39 63 10 74 1f\n RSP: 0018:ff745a70c8253898 EFLAGS: 00000282\n RAX: ff26e470054cb208 RBX: ff26e470054cb208 RCX: 000000006e958966\n RDX: ff26e48267340000 RSI: ff745a70c82539b0 RDI: ff26e458f74655c0\n RBP: 000000006e958966 R08: 0000000000000180 R09: 9cd08d909b919a89\n R10: ff26e458f74655c0 R11: 0000000000000000 R12: ff26e458f74655c0\n R13: ff745a70c82539b0 R14: d0d0d0d0d0d0d0d0 R15: 2f2f2f2f2f2f2f2f\n FS: 00007f5770896980(0000) GS:ff26e482c5d88000(0000) knlGS:0000000000000000\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 00007f5764de50c0 CR3: 000000a72abb5001 CR4: 0000000000771ef0\n PKRU: 55555554\n Call Trace:\n <TASK>\n lookup_fast+0x9f/0x100\n walk_component+0x1f/0x150\n link_path_walk+0x20e/0x3d0\n path_lookupat+0x68/0x180\n filename_lookup+0xdc/0x1e0\n vfs_statx+0x6c/0x140\n vfs_fstatat+0x67/0xa0\n __do_sys_newfstatat+0x24/0x60\n do_syscall_64+0x6a/0x230\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThis is reachable with reused cached negative dentries. A Ceph lookup\nor atomic_open can be handed a negative dentry that is already hashed,\nand fs/ceph/dir.c then hits one of two paths that incorrectly assume\n\"negative\" also means \"unhashed\":\n\n - ceph_finish_lookup():\n MDS reply is -ENOENT with no trace\n -> d_add(dentry, NULL)\n\n - ceph_lookup():\n local ENOENT fast path for a complete directory with shared caps\n -> d_add(dentry, NULL)\n\nBoth paths can therefore re-add an already-hashed negative dentry.\n\nCeph already uses the correct pattern elsewhere: ceph_fill_trace() only\ncalls d_add(dn, NULL) for a negative null-dentry reply when d_unhashed(dn)\nis true.\n\nFix both fs/ceph/dir.c sites the same way: only call d_add() for a\nnegative dentry when it is actually unhashed. If the negative dentry\nis already hashed, leave it in place and reuse it as-is.\n\nThis preserves the existing behavior for unhashed dentries while\navoiding d_hash list corruption for reused hashed negatives."
}
],
"lastModified": "2026-06-19T13:16:32.420",
"configurations": [
{
"nodes": [
{
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