cbcvebase.
CVE-2021-46990
published 2024-02-28

CVE-2021-46990: In the Linux kernel, the following vulnerability has been resolved: powerpc/64s: Fix crashes when toggling entry flush barrier The entry flush mitigation can…

PriorityP420medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.23%
14.0th percentile
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.

Affected

32 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 5.10.38-1 (bookworm)linux 5.10.38-1 (bookworm)
linuxlinux
linuxlinux
linuxlinux>= 4.14.208 < 4.14.2334.14.233
linuxlinux>= 4.19.159 < 4.19.1914.19.191
linuxlinux>= 4.4.245 < 4.4.2694.4.269
linuxlinux>= 4.9.245 < 4.9.2694.9.269
linuxlinux>= 4a1e90af718d1489ffcecc8f52486c4f5dc0f7a6 < 8382b15864e5014261b4f36c2aa89723612ee0588382b15864e5014261b4f36c2aa89723612ee058
linuxlinux>= 5.4.79 < 5.4.1205.4.120
linuxlinux>= 5.9.10 < 5.105.10
linuxlinux>= b65458b6be8032c5179d4f562038575d7b3a6be3 < 0b4eb172cc12dc102cd0ad013e53ee4463db95080b4eb172cc12dc102cd0ad013e53ee4463db9508
linuxlinux>= db01cad9efe3c3838a6b3a3f68affd295c4b92d6 < ee4b7aab93c2631c3bb0753023c5dda592bb666bee4b7aab93c2631c3bb0753023c5dda592bb666b
linuxlinux>= f69bb4e51f41973fb7594be1479fa689831efe1a < 2db22ba4e0e103f00e0512e0ecce36ac78c644f82db22ba4e0e103f00e0512e0ecce36ac78c644f8
linuxlinux>= f79643787e0a0762d2409b7b8334e83f22d85695 < d2e3590ca39ccfd8a5a46d8c7f095cb6c7b9ae92d2e3590ca39ccfd8a5a46d8c7f095cb6c7b9ae92
linuxlinux>= f79643787e0a0762d2409b7b8334e83f22d85695 < dd0d6117052faace5440db20fc37175efe921c7ddd0d6117052faace5440db20fc37175efe921c7d
linuxlinux>= f79643787e0a0762d2409b7b8334e83f22d85695 < 5bc00fdda1e934c557351a9c751a205293e68cbf5bc00fdda1e934c557351a9c751a205293e68cbf
linuxlinux>= f79643787e0a0762d2409b7b8334e83f22d85695 < aec86b052df6541cc97c5fca44e5934cbea4963baec86b052df6541cc97c5fca44e5934cbea4963b
linuxlinux>= fa4bf9f38184ed7ca4916eb64f8c767d1e279c1f < 0c25a7bb697f2e6ee65b6d63782f675bf129511a0c25a7bb697f2e6ee65b6d63782f675bf129511a
linuxlinux_kernel
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 4.4.0-253.2874.4.0-253.287
linuxlinux_kernel>= 4.14.208 < 4.14.2334.14.233

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv7.0HIGH
vendor_ubuntu7.0HIGH
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
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