Commit 90a3e375 authored by Miaohe Lin's avatar Miaohe Lin Committed by Linus Torvalds

mm/memory.c: fix potential pte_unmap_unlock pte error

Since commit 42e4089c ("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.

Andi said:

 "While the fix is correct, I'm not sure if it actually is a real bug.
  Is there any architecture that would do something else than unlocking
  the underlying page? If it's just the underlying page then it should
  be always the same page, so no bug"

Link: https://lkml.kernel.org/r/20210109080118.20885-1-linmiaohe@huawei.com
Fixes: 42e4089c ("x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings")
Signed-off-by: default avatarHongxiang Lou <louhongxiang@huawei.com>
Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b7204006
......@@ -2177,11 +2177,11 @@ 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();
......@@ -2195,7 +2195,7 @@ 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;
}
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment