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Subject[PATCH] mm: Fix potential pte_unmap_unlock pte error
Date
Since commit 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged
high MMIO PROT_NONE mappings"), when the first pfn modify is not allowed,
we would break the loop with pte unchanged. Then the wrong pte - 1 would
be passed to pte_unmap_unlock.

Fixes: 42e4089c789 ("x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings")
Signed-off-by: Hongxiang Lou <louhongxiang@huawei.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: stable@kernel.org
---
mm/memory.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index feff48e1465a..351b78ebd5a4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2165,11 +2165,11 @@ static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end,
unsigned long pfn, pgprot_t prot)
{
- pte_t *pte;
+ pte_t *pte, *mapped_pte;
spinlock_t *ptl;
int err = 0;

- pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
+ mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
if (!pte)
return -ENOMEM;
arch_enter_lazy_mmu_mode();
@@ -2183,7 +2183,7 @@ static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
pfn++;
} while (pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
- pte_unmap_unlock(pte - 1, ptl);
+ pte_unmap_unlock(mapped_pte, ptl);
return err;
}

--
2.19.1
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