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authorMiaohe Lin <linmiaohe@huawei.com>2022-05-26 19:33:50 +0800
committerakpm <akpm@linux-foundation.org>2022-05-27 08:55:18 -0700
commit24c8e27e63224ce832b4723cb60632d3eddb55de (patch)
tree7bfdfa301eb22eacbc930dbfc807823350146848 /mm
parent3e35142ef99fe6b4fe5d834ad43ee13cca10a2dc (diff)
mm/page_table_check: fix accessing unmapped ptep
ptep is unmapped too early, so ptep could theoretically be accessed while it's unmapped. This might become a problem if/when CONFIG_HIGHPTE becomes available on riscv. Fix it by deferring pte_unmap() until page table checking is done. [akpm@linux-foundation.org: account for ptep alteration, per Matthew] Link: https://lkml.kernel.org/r/20220526113350.30806-1-linmiaohe@huawei.com Fixes: 80110bbfbba6 ("mm/page_table_check: check entries at pmd levels") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_table_check.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/page_table_check.c b/mm/page_table_check.c
index 2458281bff89..bc55be28807f 100644
--- a/mm/page_table_check.c
+++ b/mm/page_table_check.c
@@ -251,11 +251,11 @@ void __page_table_check_pte_clear_range(struct mm_struct *mm,
pte_t *ptep = pte_offset_map(&pmd, addr);
unsigned long i;
- pte_unmap(ptep);
for (i = 0; i < PTRS_PER_PTE; i++) {
__page_table_check_pte_clear(mm, addr, *ptep);
addr += PAGE_SIZE;
ptep++;
}
+ pte_unmap(ptep - PTRS_PER_PTE);
}
}