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CVE-2021-47461 is an improper synchronization flaw in the Linux kernel userfaultfd subsystem. A race can occur between userfaultfd_writeprotect() and exit_mmap() when a target process exits: exit_mmap() removes the process virtual memory areas while a concurrent userfaultfd write-protection operation accesses the same memory-management state. The upstream fix obtains a nonzero reference to the target memory descriptor with mmget_not_zero(), preventing write-protect handling from racing teardown. The issue was introduced in Linux 5.7 and fixed upstream in Linux 5.10.76, 5.14.15, and 5.15.
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Linux kernel userfaultfd race condition between write protection and exit_mmap().
Linux kernel userfaultfd race condition between write-protect handling and exit_mmap().
A Linux kernel race condition involving userfaultfd write-protection handling and exit_mmap(). The issue was resolved upstream and subsequently addressed through Red Hat Enterprise Linux 8 advisories.
A Linux kernel race condition between userfaultfd_writeprotect() and exit_mmap() during process exit. Red Hat rates its impact as Moderate (CVSS 7.0), with potential confidentiality, integrity, and availability impact under its product-specific assessment.
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Cross-references every affected SKU, including bundled OEM variants.
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