Description
In the Linux kernel, the following vulnerability has been resolved: mm/vmscan: fix hwpoisoned large folio handling in shrink_folio_list In shrink_folio_list(), the hwpoisoned folio may be large folio, which can't be handled by unmap_poisoned_folio(). For THP, try_to_unmap_one() must be passed with TTU_SPLIT_HUGE_PMD to split huge PMD first and then retry. Without TTU_SPLIT_HUGE_PMD, we will trigger null-ptr deref of pvmw.pte. Even we passed TTU_SPLIT_HUGE_PMD, we will trigger a WARN_ON_ONCE due to the page isn't in swapcache. Since UCE is rare in real world, and race with reclaimation is more rare, just skipping the hwpoisoned large folio is enough. memory_failure() will handle it if the UCE is triggered again. This happens when memory reclaim for large folio races with memory_failure(), and will lead to kernel panic. The race is as follows: cpu0 cpu1 shrink_folio_list memory_failure TestSetPageHWPoison unmap_poisoned_folio --> trigger BUG_ON due to unmap_poisoned_folio couldn't handle large folio [tujinjiang@huawei.com: add comment to unmap_poisoned_folio()]
Product status
1c9798bf8145a92abf45aa9d38a6406d9eb8bdf0 (git) before 656eaddbc952e1baae2f69281c22debe22140312
1b0449544c6482179ac84530b61fc192a6527bfd (git) before c1101113d45838a823188ae25c61af97552a28ae
1b0449544c6482179ac84530b61fc192a6527bfd (git) before 9f1e8cd0b7c4c944e9921b52a6661b5eda2705ab
912e9f0300c3564b72a8808db406e313193a37ad (git)
6.15
Any version before 6.15
6.12.41 (semver)
6.15.9 (semver)
6.16 (original_commit_for_fix)
References
git.kernel.org/...c/656eaddbc952e1baae2f69281c22debe22140312
git.kernel.org/...c/c1101113d45838a823188ae25c61af97552a28ae
git.kernel.org/...c/9f1e8cd0b7c4c944e9921b52a6661b5eda2705ab
