4.7

CVE-2021-47461

userfaultfd: fix a race between writeprotect and exit_mmap()

In the Linux kernel, the following vulnerability has been resolved:

userfaultfd: fix a race between writeprotect and exit_mmap()

A race is possible when a process exits, its VMAs are removed by
exit_mmap() and at the same time userfaultfd_writeprotect() is called.

The race was detected by KASAN on a development kernel, but it appears
to be possible on vanilla kernels as well.

Use mmget_not_zero() to prevent the race as done in other userfaultfd
operations.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version >= 5.7 < 5.10.76
Linux ≫ Linux Kernel Version >= 5.11 < 5.14.15
Linux ≫ Linux Kernel Version5.15 Updaterc1
Linux ≫ Linux Kernel Version5.15 Updaterc2
Linux ≫ Linux Kernel Version5.15 Updaterc3
Linux ≫ Linux Kernel Version5.15 Updaterc4
Linux ≫ Linux Kernel Version5.15 Updaterc5
Linux ≫ Linux Kernel Version5.15 Updaterc6
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EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.16% 0.059
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
nvd@nist.gov 4.7 1 3.6
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a
Patch
https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525
Patch
https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca
Patch