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CVE-2021-47491

In the Linux kernel, the following vulnerability has been resolved: mm: khugepaged: skip huge page collapse for special files The read-only THP for filesystems…

Impact

In the Linux kernel, the following vulnerability has been resolved: mm: khugepaged: skip huge page collapse for special files The read-only THP for filesystems will collapse THP for files opened readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB misses for large text segments. But it doesn't restrict the file types so a THP could be collapsed for a non-regular file, for example, block device, if it is opened readonly and mapped with EXEC permission. This may cause bugs, like [1] and [2]. This is definitely not the intended usecase, so just collapse THP for regular files in order to close the attack surface. [shy828301@gmail.com: fix vm_file check [3]]

Affected products

VendorProductAffected versions
LinuxLinux Kernel
from 5.4 before 5.10.78
from 5.11 before 5.14.16
Version 5.15

References