Messages in this thread Patch in this message | | | From | Chih-En Lin <> | Subject | [PATCH v4 09/14] mm/mprotect: Break COW PTE before changing protection | Date | Tue, 7 Feb 2023 11:51:34 +0800 |
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If the PTE table is COW-ed, break it before changing the protection.
Signed-off-by: Chih-En Lin <shiyn.lin@gmail.com> --- mm/mprotect.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/mm/mprotect.c b/mm/mprotect.c index 61cf60015a8b..8b18cd0e5c5e 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -103,6 +103,9 @@ static unsigned long change_pte_range(struct mmu_gather *tlb, if (pmd_trans_unstable(pmd)) return 0; + if (break_cow_pte(vma, pmd, addr)) + return 0; + /* * The pmd points to a regular pte so the pmd can't change * from under us even if the mmap_lock is only hold for @@ -314,6 +317,12 @@ static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd) return 1; if (pmd_trans_huge(pmdval)) return 0; + /* + * If the entry point to COW-ed PTE, it's write protection bit + * will cause pmd_bad(). + */ + if (!pmd_write(pmdval)) + return 0; if (unlikely(pmd_bad(pmdval))) { pmd_clear_bad(pmd); return 1; -- 2.34.1
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