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:

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

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":

- 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)

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.

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4664-1 linux security update
Debian DLA Debian DLA DLA-4665-1 linux security update
Debian DLA Debian DLA DLA-4671-1 linux-6.1 security update
Ubuntu USN Ubuntu USN USN-8488-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8489-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8488-2 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-8507-1 Linux kernel (NVIDIA) vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Fri, 19 Jun 2026 12:45:00 +0000


Tue, 16 Jun 2026 15:15:00 +0000

Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:o:linux:linux_kernel:2.6.34:-:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.34:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.34:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.34:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.34:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.34:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.34:rc7:*:*:*:*:*:*

Sat, 30 May 2026 11:00:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Thu, 28 May 2026 03:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-665

Thu, 28 May 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-464
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate


Wed, 27 May 2026 18:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-665

Wed, 27 May 2026 14:15:00 +0000

Type Values Removed Values Added
Description 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: 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 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": - 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) 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.
Title ceph: only d_add() negative dentries when they are unhashed
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-06-19T11:59:10.158Z

Reserved: 2026-05-13T15:03:33.094Z

Link: CVE-2026-46052

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2026-05-27T14:17:24.807

Modified: 2026-06-17T10:52:58.337

Link: CVE-2026-46052

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-05-27T00:00:00Z

Links: CVE-2026-46052 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-06-18T02:15:15Z

Weaknesses