Bug 2309273 (CVE-2024-44947)

Summary: CVE-2024-44947 kernel: fuse: Initialize beyond-EOF page contents before setting uptodate
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Bug Depends On: 2309346    
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Description OSIDB Bzimport 2024-09-02 18:20:46 UTC 
In the Linux kernel, the following vulnerability has been resolved:

fuse: Initialize beyond-EOF page contents before setting uptodate

fuse_notify_store(), unlike fuse_do_readpage(), does not enable page
zeroing (because it can be used to change partial page contents).

So fuse_notify_store() must be more careful to fully initialize page
contents (including parts of the page that are beyond end-of-file)
before marking the page uptodate.

The current code can leave beyond-EOF page contents uninitialized, which
makes these uninitialized page contents visible to userspace via mmap().

This is an information leak, but only affects systems which do not
enable init-on-alloc (via CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y or the
corresponding kernel command line parameter).
Comment 1 Michal Findra 2024-09-03 06:12:40 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024090219-CVE-2024-44947-f49c@gregkh/T
Comment 3 errata-xmlrpc 2024-11-12 09:39:26 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