We use these services and cookies to improve your user experience. You may opt out if you wish, however, this may limit some features on this site.

Please see our statement on Data Privacy.

Zendesk (Helpdesk and Chat)
Bugpilot (Bug tracking)

Ok

THREATINT CVE Home CVE Diag Help
PUBLISHED

CVE-2021-46990

powerpc/64s: Fix crashes when toggling entry flush barrier

Reserved:2024-02-27
Published:2024-02-28
Updated:2024-04-04

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.

Product status

Default status
unaffected

4a1e90af718d before 8382b15864e5
affected

fa4bf9f38184 before 0c25a7bb697f
affected

db01cad9efe3 before ee4b7aab93c2
affected

f69bb4e51f41 before 2db22ba4e0e1
affected

b65458b6be80 before 0b4eb172cc12
affected

f79643787e0a before d2e3590ca39c
affected

f79643787e0a before dd0d6117052f
affected

f79643787e0a before 5bc00fdda1e9
affected

f79643787e0a before aec86b052df6
affected

Default status
affected

5.10
affected

Any version before 5.10
unaffected

4.4.269
unaffected

4.9.269
unaffected

4.14.233
unaffected

4.19.191
unaffected

5.4.120
unaffected

5.10.38
unaffected

5.11.22
unaffected

5.12.5
unaffected

5.13
unaffected

References

https://git.kernel.org/stable/c/8382b15864e5014261b4f36c2aa89723612ee058

https://git.kernel.org/stable/c/0c25a7bb697f2e6ee65b6d63782f675bf129511a

https://git.kernel.org/stable/c/ee4b7aab93c2631c3bb0753023c5dda592bb666b

https://git.kernel.org/stable/c/2db22ba4e0e103f00e0512e0ecce36ac78c644f8

https://git.kernel.org/stable/c/0b4eb172cc12dc102cd0ad013e53ee4463db9508

https://git.kernel.org/stable/c/d2e3590ca39ccfd8a5a46d8c7f095cb6c7b9ae92

https://git.kernel.org/stable/c/dd0d6117052faace5440db20fc37175efe921c7d

https://git.kernel.org/stable/c/5bc00fdda1e934c557351a9c751a205293e68cbf

https://git.kernel.org/stable/c/aec86b052df6541cc97c5fca44e5934cbea4963b

cve.org CVE-2021-46990

nvd.nist.gov CVE-2021-46990

Download JSON

Share this page
https://cve.threatint.com/CVE/CVE-2021-46990