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Ubuntu: (CVE-2021-47506): linux vulnerability

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Ubuntu: (CVE-2021-47506): linux vulnerability

Severity
7
CVSS
(AV:L/AC:L/Au:S/C:C/I:C/A:C)
Published
05/24/2024
Created
11/21/2024
Added
11/19/2024
Modified
02/11/2025

Description

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.

Solution(s)

  • ubuntu-upgrade-linux
  • ubuntu-upgrade-linux-aws
  • ubuntu-upgrade-linux-aws-5-4
  • ubuntu-upgrade-linux-aws-fips
  • ubuntu-upgrade-linux-aws-hwe
  • ubuntu-upgrade-linux-azure
  • ubuntu-upgrade-linux-azure-4-15
  • ubuntu-upgrade-linux-azure-5-4
  • ubuntu-upgrade-linux-azure-fips
  • ubuntu-upgrade-linux-bluefield
  • ubuntu-upgrade-linux-fips
  • ubuntu-upgrade-linux-gcp
  • ubuntu-upgrade-linux-gcp-4-15
  • ubuntu-upgrade-linux-gcp-5-4
  • ubuntu-upgrade-linux-gcp-fips
  • ubuntu-upgrade-linux-gkeop
  • ubuntu-upgrade-linux-hwe
  • ubuntu-upgrade-linux-hwe-5-4
  • ubuntu-upgrade-linux-ibm
  • ubuntu-upgrade-linux-ibm-5-4
  • ubuntu-upgrade-linux-kvm
  • ubuntu-upgrade-linux-oracle
  • ubuntu-upgrade-linux-oracle-5-4
  • ubuntu-upgrade-linux-raspi
  • ubuntu-upgrade-linux-raspi-5-4

References

  • https://attackerkb.com/topics/cve-2021-47506
  • CVE - 2021-47506
  • https://git.kernel.org/linus/548ec0805c399c65ed66c6641be467f717833ab5
  • https://git.kernel.org/stable/c/04a8d07f3d58308b92630045560799a3faa3ebce
  • https://git.kernel.org/stable/c/148c816f10fd11df27ca6a9b3238cdd42fa72cd3
  • https://git.kernel.org/stable/c/2becaa990b93cbd2928292c0b669d3abb6cf06d4
  • https://git.kernel.org/stable/c/33645d3e22720cac1e4548f8fef57bf0649536ee
  • https://git.kernel.org/stable/c/348714018139c39533c55661a0c7c990671396b4
  • https://git.kernel.org/stable/c/548ec0805c399c65ed66c6641be467f717833ab5
  • https://git.kernel.org/stable/c/e0759696de6851d7536efddfdd2dfed4c4df1f09
  • https://git.kernel.org/stable/c/eeb0711801f5e19ef654371b627682aed3b11373
  • https://www.cve.org/CVERecord?id=CVE-2021-47506
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