CVE-2021-47491: vulnerability in Linux
mm: khugepaged: skip huge page collapse for special files
Published · Updated
3Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackepss 0.2%
exploitation probability
0.2%top 90% of all CVEs
observed exploitation
nono source reports it
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
Linux · LinuxRelated CVEs — Linux
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