CVE-2022-49834: nilfs2: fix use-after-free bug of ns_writer on remount

Published May 1, 2025
·
Updated

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

nilfs2: fix use-after-free bug of nswriter on remount

If a nilfs2 filesystem is downgraded to read-only due to metadata corruption on disk and is remounted read/write, or if emergency read-only remount is performed, detaching a log writer and synchronizing the filesystem can be done at the same time.

In these cases, use-after-free of the log writer (hereinafter nilfs->nswriter) can happen as shown in the scenario below:

Task1 Task2 -------------------------------- ------------------------------ nilfsconstructsegment nilfssegctorsync initwait initwaitqueueentry addwaitqueue schedule nilfsremount (R/W remount case) nilfsattachlogwriter nilfsdetachlogwriter nilfssegctordestroy kfree finishwait rawspinlockirqsave rawspinlockirqsave dorawspinlock debugspinlockbefore <-- use-after-free

While Task1 is sleeping, nilfs->nswriter is freed by Task2. After Task1 waked up, Task1 accesses nilfs->nswriter which is already freed. This scenario diagram is based on the Shigeru Yoshida's post [1].

This patch fixes the issue by not detaching nilfs->nswriter on remount so that this UAF race doesn't happen. Along with this change, this patch also inserts a few necessary read-only checks with superblock instance where only the nswriter pointer was used to check if the filesystem is read-only.

Affected Software

175 affected componentsFixes available
Linux Kernel
Linux Linux kernel<4.9.334
Linux Linux kernel>=4.10<4.14.300
Linux Linux kernel>=4.15<4.19.267
Linux Linux kernel>=4.20<5.4.225
Linux Linux kernel>=5.5<5.10.155
Linux Linux kernel>=5.11<5.15.79
Linux Linux kernel>=5.16<6.0.9
Linux Linux kernel=6.1-rc1
Linux Linux kernel=6.1-rc2
Linux Linux kernel=6.1-rc3
Linux Linux kernel=6.1-rc4
debian/linux<6.0.10-1
6.0.10-1
debian/linux<6.0.10-1
6.0.10-1
debian/linux<6.0.10-1
6.0.10-1
debian/linux
6.1.176-16.1.190-16.12.107-16.12.115-27.2.12-17.2.15-1
ubuntu/linux-azure<4.15.0-1162.177~14.04.1
4.15.0-1162.177~14.04.1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-lts-xenial*
ubuntu/linux-aws-hwe<4.15.0-1151.164~16.04.1
4.15.0-1151.164~16.04.1
ubuntu/linux-azure<4.15.0-1162.177~16.04.1
4.15.0-1162.177~16.04.1
ubuntu/linux-gcp<4.15.0-1146.162~16.04.1
4.15.0-1146.162~16.04.1
ubuntu/linux-hwe<4.15.0-206.217~16.04.1
4.15.0-206.217~16.04.1
ubuntu/linux-oracle<4.15.0-1115.126~16.04.1
4.15.0-1115.126~16.04.1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-hwe-edge*
ubuntu/linux-kvm*
ubuntu/linux-fips*
ubuntu/linux-fips*
ubuntu/linux<4.15.0-206.217
4.15.0-206.217
ubuntu/linux-aws<4.15.0-1151.164
4.15.0-1151.164
ubuntu/linux-aws-5.4<5.4.0-1097.105~18.04.1
5.4.0-1097.105~18.04.1
ubuntu/linux-azure-4.15<4.15.0-1162.177
4.15.0-1162.177
ubuntu/linux-azure-5.4<5.4.0-1104.110~18.04.1
5.4.0-1104.110~18.04.1
ubuntu/linux-gcp-4.15<4.15.0-1146.162
4.15.0-1146.162
ubuntu/linux-gcp-5.4<5.4.0-1101.110~18.04.1
5.4.0-1101.110~18.04.1
ubuntu/linux-hwe-5.4<5.4.0-144.161~18.04.1
5.4.0-144.161~18.04.1
ubuntu/linux-ibm-5.4<5.4.0-1045.50~18.04.1
5.4.0-1045.50~18.04.1
ubuntu/linux-kvm<4.15.0-1136.141
4.15.0-1136.141
ubuntu/linux-oracle<4.15.0-1115.126
4.15.0-1115.126
ubuntu/linux-oracle-5.4<5.4.0-1094.103~18.04.1
5.4.0-1094.103~18.04.1
ubuntu/linux-raspi-5.4<5.4.0-1081.92~18.04.1
5.4.0-1081.92~18.04.1
ubuntu/linux-aws-5.0*
ubuntu/linux-aws-5.3*
ubuntu/linux-azure*
ubuntu/linux-azure-5.3*
ubuntu/linux-azure-edge*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.3*
ubuntu/linux-gke-4.15*
ubuntu/linux-gke-5.4*
ubuntu/linux-gkeop-5.4*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-oem*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux-aws-fips<4.15.0-2090.96
4.15.0-2090.96
ubuntu/linux-azure-fips<4.15.0-2071.77
4.15.0-2071.77
ubuntu/linux-fips<4.15.0-1108.119
4.15.0-1108.119
ubuntu/linux-gcp-fips<4.15.0-2055.60
4.15.0-2055.60
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<5.4.0-144.161
5.4.0-144.161
ubuntu/linux-aws<5.4.0-1097.105
5.4.0-1097.105
ubuntu/linux-aws-5.15<5.15.0-1031.35~20.04.1
5.15.0-1031.35~20.04.1
ubuntu/linux-azure<5.4.0-1104.110
5.4.0-1104.110
ubuntu/linux-azure-5.15<5.15.0-1034.41~20.04.1
5.15.0-1034.41~20.04.1
ubuntu/linux-bluefield<5.4.0-1059.65
5.4.0-1059.65
ubuntu/linux-gcp<5.4.0-1101.110
5.4.0-1101.110
ubuntu/linux-gcp-5.15<5.15.0-1030.37~20.04.1
5.15.0-1030.37~20.04.1
ubuntu/linux-hwe-5.15<5.15.0-67.74~20.04.1
5.15.0-67.74~20.04.1
ubuntu/linux-ibm<5.4.0-1045.50
5.4.0-1045.50
ubuntu/linux-intel-iotg-5.15<5.15.0-1026.31~20.04.1
5.15.0-1026.31~20.04.1
ubuntu/linux-iot<5.4.0-1013.15
5.4.0-1013.15
ubuntu/linux-kvm<5.4.0-1087.93
5.4.0-1087.93
ubuntu/linux-lowlatency-hwe-5.15<5.15.0-67.74~20.04.1
5.15.0-67.74~20.04.1
ubuntu/linux-nvidia-tegra-5.15<5.15.0-1014.14~20.04.1
5.15.0-1014.14~20.04.1
ubuntu/linux-oracle<5.4.0-1094.103
5.4.0-1094.103
ubuntu/linux-oracle-5.15<5.15.0-1030.36~20.04.1
5.15.0-1030.36~20.04.1
ubuntu/linux-raspi<5.4.0-1081.92
5.4.0-1081.92
ubuntu/linux-riscv-5.15<5.15.0-1030.34~20.04.1
5.15.0-1030.34~20.04.1
ubuntu/linux-xilinx-zynqmp<5.4.0-1022.26
5.4.0-1022.26
ubuntu/linux-aws-5.11*
ubuntu/linux-aws-5.13*
ubuntu/linux-aws-5.8*
ubuntu/linux-azure-5.11*
ubuntu/linux-azure-5.13*
ubuntu/linux-azure-5.8*
ubuntu/linux-azure-fde*
ubuntu/linux-gcp-5.11*
ubuntu/linux-gcp-5.13*
ubuntu/linux-gcp-5.8*
ubuntu/linux-gke*
ubuntu/linux-gke-5.15*
ubuntu/linux-gkeop*
ubuntu/linux-gkeop-5.15*
ubuntu/linux-hwe-5.11*
ubuntu/linux-hwe-5.13*
ubuntu/linux-hwe-5.8*
ubuntu/linux-intel-5.13*
ubuntu/linux-oem-5.10*
ubuntu/linux-oem-5.13*
ubuntu/linux-oem-5.6*
ubuntu/linux-oracle-5.11*
ubuntu/linux-oracle-5.13*
ubuntu/linux-oracle-5.8*
ubuntu/linux-raspi2*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.11*
ubuntu/linux-riscv-5.8*
ubuntu/linux-aws-fips<5.4.0-1099.107+fips1
5.4.0-1099.107+fips1
ubuntu/linux-azure-fips<5.4.0-1104.110+fips1
5.4.0-1104.110+fips1
ubuntu/linux-fips<5.4.0-1073.82
5.4.0-1073.82
ubuntu/linux-gcp-fips<5.4.0-1101.110+fips1
5.4.0-1101.110+fips1
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<5.15.0-67.74
5.15.0-67.74
ubuntu/linux-allwinner-5.19*
ubuntu/linux-aws<5.15.0-1031.35
5.15.0-1031.35
ubuntu/linux-aws-5.19*
ubuntu/linux-aws-6.2*
ubuntu/linux-aws-6.5*
ubuntu/linux-azure<5.15.0-1034.41
5.15.0-1034.41
ubuntu/linux-azure-5.19*
ubuntu/linux-azure-6.2*
ubuntu/linux-azure-6.5*
ubuntu/linux-azure-fde<5.15.0-1034.41.1
5.15.0-1034.41.1
ubuntu/linux-azure-fde-5.19*
ubuntu/linux-azure-fde-6.2*
ubuntu/linux-gcp<5.15.0-1030.37
5.15.0-1030.37
ubuntu/linux-gcp-5.19*
ubuntu/linux-gcp-6.2*
ubuntu/linux-gcp-6.5*
ubuntu/linux-gke<5.15.0-1028.33
5.15.0-1028.33
ubuntu/linux-gkeop<5.15.0-1016.21
5.15.0-1016.21
ubuntu/linux-hwe-5.19*
ubuntu/linux-hwe-6.2*
ubuntu/linux-hwe-6.5*
ubuntu/linux-ibm<5.15.0-1026.29
5.15.0-1026.29
ubuntu/linux-intel-iotg<5.15.0-1026.31
5.15.0-1026.31
ubuntu/linux-kvm<5.15.0-1029.34
5.15.0-1029.34
ubuntu/linux-lowlatency<5.15.0-67.74
5.15.0-67.74
ubuntu/linux-lowlatency-hwe-5.19*
ubuntu/linux-lowlatency-hwe-6.2*
ubuntu/linux-lowlatency-hwe-6.5*
ubuntu/linux-nvidia<5.15.0-1023.23
5.15.0-1023.23
ubuntu/linux-nvidia-6.2*
ubuntu/linux-nvidia-6.5*
ubuntu/linux-oem-5.17*
ubuntu/linux-oem-6.0*
ubuntu/linux-oem-6.1*
ubuntu/linux-oem-6.5*
ubuntu/linux-oracle<5.15.0-1030.36
5.15.0-1030.36
ubuntu/linux-oracle-6.5*
ubuntu/linux-raspi<5.15.0-1025.27
5.15.0-1025.27
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.19*
ubuntu/linux-riscv-6.5*
ubuntu/linux-starfive-5.19*
ubuntu/linux-starfive-6.2*
ubuntu/linux-starfive-6.5*
ubuntu/linux-bluefield<5.15.0-1014.16
5.15.0-1014.16
ubuntu/linux-intel-iot-realtime<5.15.0-1022.27
5.15.0-1022.27
ubuntu/linux-realtime<5.15.0-1033.36
5.15.0-1033.36
ubuntu/linux-raspi-realtime*
ubuntu/linux-realtime*
ubuntu/linux-vmware*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

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    Fixed in 6.0.10-1
  2. Upgrade

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    Fixed in 6.1.176-1Fixed in 6.1.190-1Fixed in 6.12.107-1Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1
  3. Upgrade

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    Fixed in 4.15.0-1162.177~14.04.1
  4. Upgrade

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    Fixed in 4.15.0-1151.164~16.04.1
  5. Upgrade

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    Fixed in 4.15.0-1162.177~16.04.1
  6. Upgrade

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    Fixed in 4.15.0-1146.162~16.04.1
  7. Upgrade

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    Fixed in 4.15.0-206.217~16.04.1
  8. Upgrade

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    Fixed in 4.15.0-1115.126~16.04.1
  9. Upgrade

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    Fixed in 4.15.0-206.217
  10. Upgrade

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    Fixed in 4.15.0-1151.164
  11. Upgrade

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    Fixed in 5.4.0-1097.105~18.04.1
  12. Upgrade

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    Fixed in 4.15.0-1162.177
  13. Upgrade

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    Fixed in 5.4.0-1104.110~18.04.1
  14. Upgrade

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    Fixed in 4.15.0-1146.162
  15. Upgrade

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    Fixed in 5.4.0-1101.110~18.04.1
  16. Upgrade

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    Fixed in 5.4.0-144.161~18.04.1
  17. Upgrade

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    Fixed in 5.4.0-1045.50~18.04.1
  18. Upgrade

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    Fixed in 4.15.0-1136.141
  19. Upgrade

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    Fixed in 4.15.0-1115.126
  20. Upgrade

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    Fixed in 5.4.0-1094.103~18.04.1
  21. Upgrade

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    Fixed in 5.4.0-1081.92~18.04.1
  22. Upgrade

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    Fixed in 4.15.0-2090.96
  23. Upgrade

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    Fixed in 4.15.0-2071.77
  24. Upgrade

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    Fixed in 4.15.0-1108.119
  25. Upgrade

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    Fixed in 4.15.0-2055.60
  26. Upgrade

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    Fixed in 5.4.0-144.161
  27. Upgrade

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    Fixed in 5.4.0-1097.105
  28. Upgrade

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    Fixed in 5.15.0-1031.35~20.04.1
  29. Upgrade

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    Fixed in 5.4.0-1104.110
  30. Upgrade

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    Fixed in 5.15.0-1034.41~20.04.1
  31. Upgrade

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    Fixed in 5.4.0-1059.65
  32. Upgrade

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    Fixed in 5.4.0-1101.110
  33. Upgrade

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    Fixed in 5.15.0-1030.37~20.04.1
  34. Upgrade

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    Fixed in 5.15.0-67.74~20.04.1
  35. Upgrade

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    Fixed in 5.4.0-1045.50
  36. Upgrade

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    Fixed in 5.15.0-1026.31~20.04.1
  37. Upgrade

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    Fixed in 5.4.0-1013.15
  38. Upgrade

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    Fixed in 5.4.0-1087.93
  39. Upgrade

    Upgrade ubuntu/linux-lowlatency-hwe-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-67.74~20.04.1
  40. Upgrade

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    Fixed in 5.15.0-1014.14~20.04.1
  41. Upgrade

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    Fixed in 5.4.0-1094.103
  42. Upgrade

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    Fixed in 5.15.0-1030.36~20.04.1
  43. Upgrade

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    Fixed in 5.4.0-1081.92
  44. Upgrade

    Upgrade ubuntu/linux-riscv-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1030.34~20.04.1
  45. Upgrade

    Upgrade ubuntu/linux-xilinx-zynqmp to a version that resolves this vulnerability.

    Fixed in 5.4.0-1022.26
  46. Upgrade

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    Fixed in 5.4.0-1099.107+fips1
  47. Upgrade

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    Fixed in 5.4.0-1104.110+fips1
  48. Upgrade

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    Fixed in 5.4.0-1073.82
  49. Upgrade

    Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.

    Fixed in 5.4.0-1101.110+fips1
  50. Upgrade

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    Fixed in 5.15.0-67.74
  51. Upgrade

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    Fixed in 5.15.0-1031.35
  52. Upgrade

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    Fixed in 5.15.0-1034.41
  53. Upgrade

    Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.

    Fixed in 5.15.0-1034.41.1
  54. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 5.15.0-1030.37
  55. Upgrade

    Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.

    Fixed in 5.15.0-1028.33
  56. Upgrade

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    Fixed in 5.15.0-1016.21
  57. Upgrade

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    Fixed in 5.15.0-1026.29
  58. Upgrade

    Upgrade ubuntu/linux-intel-iotg to a version that resolves this vulnerability.

    Fixed in 5.15.0-1026.31
  59. Upgrade

    Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.

    Fixed in 5.15.0-1029.34
  60. Upgrade

    Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.

    Fixed in 5.15.0-67.74
  61. Upgrade

    Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.

    Fixed in 5.15.0-1023.23
  62. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 5.15.0-1030.36
  63. Upgrade

    Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.

    Fixed in 5.15.0-1025.27
  64. Upgrade

    Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.

    Fixed in 5.15.0-1014.16
  65. Upgrade

    Upgrade ubuntu/linux-intel-iot-realtime to a version that resolves this vulnerability.

    Fixed in 5.15.0-1022.27
  66. Upgrade

    Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.

    Fixed in 5.15.0-1033.36

Event History

May 1, 2025
CVE Published
via MITRE·02:09 PM
Data Sourced
via MITRE·02:09 PM
DescriptionSeverity
Data Sourced
via OSV·03:16 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·03:16 PM
RemedyDescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the severity of CVE-2022-49834?

CVE-2022-49834 is considered a high-severity vulnerability due to the potential exploitation leading to system instability.

2

How do I fix CVE-2022-49834?

To fix CVE-2022-49834, update the Linux kernel to a version that includes the patch for this vulnerability.

3

Which versions of the Linux kernel are affected by CVE-2022-49834?

CVE-2022-49834 affects various versions of the Linux kernel, including those up to 6.1-rc4.

4

What is the nature of the vulnerability described in CVE-2022-49834?

CVE-2022-49834 is a use-after-free bug related to the nilfs2 filesystem in the Linux kernel.

5

Can CVE-2022-49834 lead to data loss?

Yes, CVE-2022-49834 can potentially lead to data loss if the vulnerability is exploited while interacting with a nilfs2 filesystem.

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