Bug 2300364 (CVE-2024-41021)

Summary: CVE-2024-41021 kernel: s390/mm: Fix VM_FAULT_HWPOISON handling in do_exception()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: kernel 6.9.12, kernel 6.10.2, kernel 6.11-rc1 Doc Type: If docs needed, set a value
Doc Text:
A vulnerability was found in the Linux kernel in the function do_fault_error() where it is possible for a VM_FAULT_HWPOISON memory fault to appear in combination with PTE_MARKER_POISONED, even though the s390 architecture does not support HWPOISON. This can result in improper memory management and lead to crashes or kernel panics.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2300897    
Bug Blocks:    

Description OSIDB Bzimport 2024-07-29 14:20:51 UTC
In the Linux kernel, the following vulnerability has been resolved:

s390/mm: Fix VM_FAULT_HWPOISON handling in do_exception()

There is no support for HWPOISON, MEMORY_FAILURE, or ARCH_HAS_COPY_MC on
s390. Therefore we do not expect to see VM_FAULT_HWPOISON in
do_exception().

However, since commit af19487f00f3 ("mm: make PTE_MARKER_SWAPIN_ERROR more
general"), it is possible to see VM_FAULT_HWPOISON in combination with
PTE_MARKER_POISONED, even on architectures that do not support HWPOISON
otherwise. In this case, we will end up on the BUG() in do_exception().

Fix this by treating VM_FAULT_HWPOISON the same as VM_FAULT_SIGBUS, similar
to x86 when MEMORY_FAILURE is not configured. Also print unexpected fault
flags, for easier debugging.

Note that VM_FAULT_HWPOISON_LARGE is not expected, because s390 cannot
support swap entries on other levels than PTE level.

Comment 1 Mauro Matteo Cascella 2024-07-29 19:15:43 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2300897]