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SUSE: CVE-2021-46988: SUSE Linux Security Advisory

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SUSE: CVE-2021-46988: SUSE Linux Security Advisory

Severity
5
CVSS
(AV:L/AC:L/Au:S/C:N/I:N/A:C)
Published
02/28/2024
Created
08/16/2024
Added
08/09/2024
Modified
01/28/2025

Description

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: release page in error path to avoid BUG_ON Consider the following sequence of events: 1. Userspace issues a UFFD ioctl, which ends up calling into shmem_mfill_atomic_pte(). We successfully account the blocks, we shmem_alloc_page(), but then the copy_from_user() fails. We return -ENOENT. We don't release the page we allocated. 2. Our caller detects this error code, tries the copy_from_user() after dropping the mmap_lock, and retries, calling back into shmem_mfill_atomic_pte(). 3. Meanwhile, let's say another process filled up the tmpfs being used. 4. So shmem_mfill_atomic_pte() fails to account blocks this time, and immediately returns - without releasing the page. This triggers a BUG_ON in our caller, which asserts that the page should always be consumed, unless -ENOENT is returned. To fix this, detect if we have such a "dangling" page when accounting fails, and if so, release it before returning.

Solution(s)

  • suse-upgrade-kernel-64kb
  • suse-upgrade-kernel-64kb-devel
  • suse-upgrade-kernel-azure
  • suse-upgrade-kernel-azure-base
  • suse-upgrade-kernel-azure-devel
  • suse-upgrade-kernel-default
  • suse-upgrade-kernel-default-base
  • suse-upgrade-kernel-default-devel
  • suse-upgrade-kernel-default-extra
  • suse-upgrade-kernel-default-man
  • suse-upgrade-kernel-devel
  • suse-upgrade-kernel-devel-azure
  • suse-upgrade-kernel-docs
  • suse-upgrade-kernel-macros
  • suse-upgrade-kernel-obs-build
  • suse-upgrade-kernel-preempt
  • suse-upgrade-kernel-preempt-devel
  • suse-upgrade-kernel-source
  • suse-upgrade-kernel-source-azure
  • suse-upgrade-kernel-syms
  • suse-upgrade-kernel-syms-azure
  • suse-upgrade-kernel-zfcpdump
  • suse-upgrade-reiserfs-kmp-default

References

  • https://attackerkb.com/topics/cve-2021-46988
  • CVE - 2021-46988
  • 查看数 703
  • 已创建
  • 最后回复

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