Vulnerability CVE-2024-44947
Published: 2024-09-02

Description:
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).

 References:
https://git.kernel.org/stable/c/831433527773e665bdb635ab5783d0b95d1246f4
https://git.kernel.org/stable/c/ac42e0f0eb66af966015ee33fd355bc6f5d80cd6
https://git.kernel.org/stable/c/18a067240817bee8a9360539af5d79a4bf5398a5
https://git.kernel.org/stable/c/3c0da3d163eb32f1f91891efaade027fa9b245b9
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