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    Subject[PATCH 4.19 20/78] x86/mm/mem_encrypt: Fix erroneous sizeof()
    Date
    4.19-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    [ Upstream commit bf7d28c53453ea904584960de55e33e03b9d93b1 ]

    Using sizeof(pointer) for determining the size of a memset() only works
    when the size of the pointer and the size of type to which it points are
    the same. For pte_t this is only true for 64bit and 32bit-NONPAE. On 32bit
    PAE systems this is wrong as the pointer size is 4 byte but the PTE entry
    is 8 bytes. It's actually not a real world issue as this code depends on
    64bit, but it's wrong nevertheless.

    Use sizeof(*p) for correctness sake.

    Fixes: aad983913d77 ("x86/mm/encrypt: Simplify sme_populate_pgd() and sme_populate_pgd_large()")
    Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Cc: Tom Lendacky <thomas.lendacky@amd.com>
    Cc: dave.hansen@linux.intel.com
    Cc: peterz@infradead.org
    Cc: luto@kernel.org
    Link: https://lkml.kernel.org/r/1546065252-97996-1-git-send-email-peng.hao2@zte.com.cn
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/mm/mem_encrypt_identity.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
    index 7ae36868aed25..c9faf34cbb62e 100644
    --- a/arch/x86/mm/mem_encrypt_identity.c
    +++ b/arch/x86/mm/mem_encrypt_identity.c
    @@ -157,8 +157,8 @@ static void __init sme_populate_pgd(struct sme_populate_pgd_data *ppd)
    pmd = pmd_offset(pud, ppd->vaddr);
    if (pmd_none(*pmd)) {
    pte = ppd->pgtable_area;
    - memset(pte, 0, sizeof(pte) * PTRS_PER_PTE);
    - ppd->pgtable_area += sizeof(pte) * PTRS_PER_PTE;
    + memset(pte, 0, sizeof(*pte) * PTRS_PER_PTE);
    + ppd->pgtable_area += sizeof(*pte) * PTRS_PER_PTE;
    set_pmd(pmd, __pmd(PMD_FLAGS | __pa(pte)));
    }

    --
    2.19.1


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