nfsd: fix use-after-free due to delegation race
A delegation break could arrive as soon as we've called vfs_setlease. A
delegation break runs a callback which immediately (in
nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we
then exit nfs4_set_delegation without hashing the delegation, it will be
freed as soon as the callback is done with it, without ever being
removed from del_recall_lru.
Symptoms show up later as use-after-free or list corruption warnings,
usually in the laundromat thread.
I suspect aba2072f4523 "nfsd: grant read delegations to clients holding
writes" made this bug easier to hit, but I looked as far back as v3.0
and it looks to me it already had the same problem. So I'm not sure
where the bug was introduced; it may have been there from the beginning.
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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| Source | ID | Title |
|---|---|---|
Ubuntu USN |
USN-7506-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7506-2 | Linux kernel (AWS) vulnerabilities |
Ubuntu USN |
USN-7506-3 | Linux kernel (FIPS) vulnerabilities |
Ubuntu USN |
USN-7506-4 | Linux kernel (Xenial HWE) vulnerabilities |
Wed, 16 Jul 2025 13:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
epss
|
epss
|
Mon, 06 Jan 2025 21:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:* |
|
| Vendors & Products |
Linux
Linux linux Kernel |
|
| Metrics |
cvssV3_1
|
cvssV3_1
|
Mon, 04 Nov 2024 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-11T13:55:58.110Z
Reserved: 2024-05-22T06:20:56.205Z
Link: CVE-2021-47506
Updated: 2024-08-04T05:39:59.751Z
Status : Analyzed
Published: 2024-05-24T15:15:11.197
Modified: 2025-01-06T20:44:45.983
Link: CVE-2021-47506
OpenCVE Enrichment
No data.
Ubuntu USN