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Ubuntu: (CVE-2022-48892): linux vulnerability

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Ubuntu: (CVE-2022-48892): linux vulnerability

Severity
7
CVSS
(AV:L/AC:L/Au:S/C:C/I:C/A:C)
Published
08/21/2024
Created
11/21/2024
Added
11/19/2024
Modified
02/11/2025

Description

In the Linux kernel, the following vulnerability has been resolved: sched/core: Fix use-after-free bug in dup_user_cpus_ptr() Since commit 07ec77a1d4e8 ("sched: Allow task CPU affinity to be restricted on asymmetric systems"), the setting and clearing of user_cpus_ptr are done under pi_lock for arm64 architecture. However, dup_user_cpus_ptr() accesses user_cpus_ptr without any lock protection. Since sched_setaffinity() can be invoked from another process, the process being modified may be undergoing fork() at the same time.When racing with the clearing of user_cpus_ptr in __set_cpus_allowed_ptr_locked(), it can lead to user-after-free and possibly double-free in arm64 kernel. Commit 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask") fixes this problem as user_cpus_ptr, once set, will never be cleared in a task's lifetime. However, this bug was re-introduced in commit 851a723e45d1 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()") which allows the clearing of user_cpus_ptr in do_set_cpus_allowed(). This time, it will affect all arches. Fix this bug by always clearing the user_cpus_ptr of the newly cloned/forked task before the copying process starts and check the user_cpus_ptr state of the source task under pi_lock. Note to stable, this patch won't be applicable to stable releases. Just copy the new dup_user_cpus_ptr() function over.

Solution(s)

  • ubuntu-upgrade-linux
  • ubuntu-upgrade-linux-aws
  • ubuntu-upgrade-linux-aws-5-15
  • ubuntu-upgrade-linux-azure
  • ubuntu-upgrade-linux-azure-5-15
  • ubuntu-upgrade-linux-azure-fde
  • ubuntu-upgrade-linux-azure-fde-5-15
  • ubuntu-upgrade-linux-bluefield
  • ubuntu-upgrade-linux-gcp
  • ubuntu-upgrade-linux-gcp-5-15
  • ubuntu-upgrade-linux-gke
  • ubuntu-upgrade-linux-gkeop
  • ubuntu-upgrade-linux-gkeop-5-15
  • ubuntu-upgrade-linux-hwe-5-15
  • ubuntu-upgrade-linux-ibm
  • ubuntu-upgrade-linux-intel-iot-realtime
  • ubuntu-upgrade-linux-intel-iotg
  • ubuntu-upgrade-linux-intel-iotg-5-15
  • ubuntu-upgrade-linux-kvm
  • ubuntu-upgrade-linux-lowlatency
  • ubuntu-upgrade-linux-lowlatency-hwe-5-15
  • ubuntu-upgrade-linux-nvidia
  • ubuntu-upgrade-linux-oracle
  • ubuntu-upgrade-linux-oracle-5-15
  • ubuntu-upgrade-linux-raspi
  • ubuntu-upgrade-linux-realtime
  • ubuntu-upgrade-linux-riscv-5-15

References

  • https://attackerkb.com/topics/cve-2022-48892
  • CVE - 2022-48892
  • https://git.kernel.org/linus/87ca4f9efbd7cc649ff43b87970888f2812945b8
  • https://git.kernel.org/stable/c/7b5cc7fd1789ea5dbb942c9f8207b076d365badc
  • https://git.kernel.org/stable/c/87ca4f9efbd7cc649ff43b87970888f2812945b8
  • https://git.kernel.org/stable/c/b22faa21b6230d5eccd233e1b7e0026a5002b287
  • https://www.cve.org/CVERecord?id=CVE-2022-48892
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