Bug 2309796 (CVE-2024-44965)

Summary: CVE-2024-44965 kernel: x86/mm: Fix pti_clone_pgtable() alignment assumption
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Bug Depends On: 2309899    
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Description OSIDB Bzimport 2024-09-04 19:21:12 UTC 
In the Linux kernel, the following vulnerability has been resolved:

x86/mm: Fix pti_clone_pgtable() alignment assumption

Guenter reported dodgy crashes on an i386-nosmp build using GCC-11
that had the form of endless traps until entry stack exhaust and then
#DF from the stack guard.

It turned out that pti_clone_pgtable() had alignment assumptions on
the start address, notably it hard assumes start is PMD aligned. This
is true on x86_64, but very much not true on i386.

These assumptions can cause the end condition to malfunction, leading
to a 'short' clone. Guess what happens when the user mapping has a
short copy of the entry text?

Use the correct increment form for addr to avoid alignment
assumptions.
Comment 1 Robb Gatica 2024-09-04 20:36:32 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024090415-CVE-2024-44965-d41d@gregkh/T
Comment 3 errata-xmlrpc 2024-11-12 09:36:39 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2024:9315 https://access.redhat.com/errata/RHSA-2024:9315