Bug 2301542 (CVE-2024-42224)

Summary: CVE-2024-42224 kernel: net: dsa: mv88e6xxx: Correct check for empty list
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A vulnerability was found in the Linux kernel's mv88e6xxx driver in the mv88e6xxx_default_mdio_bus() function, where an improper check for an empty linked list could lead to dereferencing a potentially invalid pointer. This issue could lead to memory corruption or crashes.
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Bug Depends On: 2302251    
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Description OSIDB Bzimport 2024-07-30 09:09:22 UTC
In the Linux kernel, the following vulnerability has been resolved:

net: dsa: mv88e6xxx: Correct check for empty list

Since commit a3c53be55c95 ("net: dsa: mv88e6xxx: Support multiple MDIO
busses") mv88e6xxx_default_mdio_bus() has checked that the
return value of list_first_entry() is non-NULL.

This appears to be intended to guard against the list chip->mdios being
empty.  However, it is not the correct check as the implementation of
list_first_entry is not designed to return NULL for empty lists.

Instead, use list_first_entry_or_null() which does return NULL if the
list is empty.

Flagged by Smatch.
Compile tested only.