CVE-2023-52566

In the Linux kernel, the following vulnerability has been resolved: nilfs2:
fix potential use after free in nilfs_gccache_submit_read_data() In
nilfs_gccache_submit_read_data(), brelse(bh) is called to drop the
reference count of bh when the call to nilfs_dat_translate() fails. If the
reference count hits 0 and its owner page gets unlocked, bh may be freed.
However, bh->b_page is dereferenced to put the page after that, which may
result in a use-after-free bug. This patch moves the release operation
after unlocking and putting the page. NOTE: The function in question is
only called in GC, and in combination with current userland tools, address
translation using DAT does not occur in that function, so the code path
that causes this issue will not be executed. However, it is possible to run
that code path by intentionally modifying the userland GC library or by
calling the GC ioctl directly. [[email protected]: NOTE added to
the commit log]