From cc6f0e39000900e5dd1448103a9571f0eccd7d4e Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Sat, 7 Mar 2020 10:09:15 +0000 Subject: [PATCH] powerpc/32: Fix missing NULL pmd check in virt_to_kpte() Commit 2efc7c085f05 ("powerpc/32: drop get_pteptr()"), replaced get_pteptr() by virt_to_kpte(). But virt_to_kpte() lacks a NULL pmd check and returns an invalid non NULL pointer when there is no page table. Reported-by: Nick Desaulniers Fixes: 2efc7c085f05 ("powerpc/32: drop get_pteptr()") Signed-off-by: Christophe Leroy Tested-by: Nathan Chancellor Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/b1177cdfc6af74a3e277bba5d9e708c4b3315ebe.1583575707.git.christophe.leroy@c-s.fr --- arch/powerpc/include/asm/pgtable.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h index b80bfd4..b1f1d53 100644 --- a/arch/powerpc/include/asm/pgtable.h +++ b/arch/powerpc/include/asm/pgtable.h @@ -54,7 +54,9 @@ static inline pmd_t *pmd_ptr_k(unsigned long va) static inline pte_t *virt_to_kpte(unsigned long vaddr) { - return pte_offset_kernel(pmd_ptr_k(vaddr), vaddr); + pmd_t *pmd = pmd_ptr_k(vaddr); + + return pmd_none(*pmd) ? NULL : pte_offset_kernel(pmd, vaddr); } #endif -- 2.7.4