CVE-2021-46990
Linux Kernel PowerPC 64s stop_machine Debugfs Execution Flutter
Description
In the Linux kernel, the following vulnerability has been resolved: powerpc/64s: Fix crashes when toggling entry flush barrier The entry flush mitigation can be enabled/disabled at runtime via a debugfs file (entry_flush), which causes the kernel to patch itself to enable/disable the relevant mitigations. However depending on which mitigation we're using, it may not be safe to do that patching while other CPUs are active. For example the following crash: sleeper[15639]: segfault (11) at c000000000004c20 nip c000000000004c20 lr c000000000004c20 Shows that we returned to userspace with a corrupted LR that points into the kernel, due to executing the partially patched call to the fallback entry flush (ie. we missed the LR restore). Fix it by doing the patching under stop machine. The CPUs that aren't doing the patching will be spinning in the core of the stop machine logic. That is currently sufficient for our purposes, because none of the patching we do is to that code or anywhere in the vicinity.
INFO
Published Date :
Feb. 28, 2024, 9:15 a.m.
Last Modified :
Feb. 28, 2024, 2:06 p.m.
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Remotely Exploitable :
No
Impact Score :
Exploitability Score :
References to Advisories, Solutions, and Tools
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information, practical solutions, and valuable tools related to
CVE-2021-46990
.
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The following list is the news that have been mention
CVE-2021-46990
vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-46990
vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
May. 28, 2024
Action Type Old Value New Value -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
May. 14, 2024
Action Type Old Value New Value -
CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Feb. 28, 2024
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: powerpc/64s: Fix crashes when toggling entry flush barrier The entry flush mitigation can be enabled/disabled at runtime via a debugfs file (entry_flush), which causes the kernel to patch itself to enable/disable the relevant mitigations. However depending on which mitigation we're using, it may not be safe to do that patching while other CPUs are active. For example the following crash: sleeper[15639]: segfault (11) at c000000000004c20 nip c000000000004c20 lr c000000000004c20 Shows that we returned to userspace with a corrupted LR that points into the kernel, due to executing the partially patched call to the fallback entry flush (ie. we missed the LR restore). Fix it by doing the patching under stop machine. The CPUs that aren't doing the patching will be spinning in the core of the stop machine logic. That is currently sufficient for our purposes, because none of the patching we do is to that code or anywhere in the vicinity. Added Reference Linux https://git.kernel.org/stable/c/8382b15864e5014261b4f36c2aa89723612ee058 [No types assigned] Added Reference Linux https://git.kernel.org/stable/c/0c25a7bb697f2e6ee65b6d63782f675bf129511a [No types assigned] Added Reference Linux https://git.kernel.org/stable/c/ee4b7aab93c2631c3bb0753023c5dda592bb666b [No types assigned] Added Reference Linux https://git.kernel.org/stable/c/2db22ba4e0e103f00e0512e0ecce36ac78c644f8 [No types assigned] Added Reference Linux https://git.kernel.org/stable/c/0b4eb172cc12dc102cd0ad013e53ee4463db9508 [No types assigned] Added Reference Linux https://git.kernel.org/stable/c/d2e3590ca39ccfd8a5a46d8c7f095cb6c7b9ae92 [No types assigned] Added Reference Linux https://git.kernel.org/stable/c/dd0d6117052faace5440db20fc37175efe921c7d [No types assigned] Added Reference Linux https://git.kernel.org/stable/c/5bc00fdda1e934c557351a9c751a205293e68cbf [No types assigned] Added Reference Linux https://git.kernel.org/stable/c/aec86b052df6541cc97c5fca44e5934cbea4963b [No types assigned]
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-46990
is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-46990
weaknesses.