7.8

CVE-2021-47506

In the Linux kernel, the following vulnerability has been resolved:

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.
Data is provided by the National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version < 4.4.296
Linux ≫ Linux Kernel Version >= 4.5 < 4.9.294
Linux ≫ Linux Kernel Version >= 4.10 < 4.14.259
Linux ≫ Linux Kernel Version >= 4.15 < 4.19.222
Linux ≫ Linux Kernel Version >= 4.20 < 5.4.168
Linux ≫ Linux Kernel Version >= 5.5 < 5.10.85
Linux ≫ Linux Kernel Version >= 5.11 < 5.15.8
Linux ≫ Linux Kernel Version5.15 Updaterc1
Linux ≫ Linux Kernel Version5.15 Updaterc2
Linux ≫ Linux Kernel Version5.15 Updaterc3
Linux ≫ Linux Kernel Version5.15 Updaterc4
Zu dieser CVE wurde keine CISA KEV oder CERT.AT-Warnung gefunden.
EPSS Metriken
Type Source Score Percentile
EPSS FIRST.org 0.01% 0.01
CVSS Metriken
Source Base Score Exploit Score Impact Score Vector string
nvd@nist.gov 7.8 1.8 5.9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE-416 Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.