title: mm: cachestat: fix folio read-after-free in cache walk
description: 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.
affected:
{
product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: cf264e1329fb, lessThan: ba60fdf75e89, status: affected, versionType: git
version: cf264e1329fb, lessThan: fe7e008e0ce7, status: affected, versionType: git
version: cf264e1329fb, lessThan: 3a75cb05d53f, status: affected, versionType: git
}
{
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 6.5, status: affected
version: 0, lessThan: 6.5, status: unaffected, versionType: custom
version: 6.6.21, lessThanOrEqual: 6.6.*, status: unaffected, versionType: custom
version: 6.7.9, lessThanOrEqual: 6.7.*, status: unaffected, versionType: custom
version: 6.8, lessThanOrEqual: *, status: unaffected, versionType: original_commit_for_fix
}
