CVE-2024-26630

In the Linux kernel, the following vulnerability has been resolved: mm:
cachestat: fix folio read-after-free in cache walk In cachestat, we access
the folio from the page cache’s xarray to compute its page offset, and
check for its dirty and writeback flags. However, we do not hold a
reference to the folio before performing these actions, which means the
folio can concurrently be released and reused as another folio/page/slab.
Get around this altogether by just using xarray’s existing machinery for
the folio page offsets and dirty/writeback states. This changes behavior
for tmpfs files to now always report zeroes in their dirty and writeback
counters. This is okay as tmpfs doesn’t follow conventional writeback cache
behavior: its pages get “cleaned” during swapout, after which they’re no
longer resident etc.