Bug 2348099 (CVE-2022-49699)

Summary: CVE-2022-49699 kernel: filemap: Handle sibling entries in filemap_get_read_batch()
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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Description OSIDB Bzimport 2025-02-26 03:17:35 UTC 
In the Linux kernel, the following vulnerability has been resolved:

filemap: Handle sibling entries in filemap_get_read_batch()

If a read races with an invalidation followed by another read, it is
possible for a folio to be replaced with a higher-order folio.  If that
happens, we'll see a sibling entry for the new folio in the next iteration
of the loop.  This manifests as a NULL pointer dereference while holding
the RCU read lock.

Handle this by simply returning.  The next call will find the new folio
and handle it correctly.  The other ways of handling this rare race are
more complex and it's just not worth it.
Comment 1 Avinash Hanwate 2025-02-26 19:04:17 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025022628-CVE-2022-49699-d60e@gregkh/T