From 0e311d237d7f3022b7dafb639b42541bfb42fe94 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Mon, 25 Jun 2018 13:24:27 +0300 Subject: x86/mm: Don't free P4D table when it is folded at runtime When the P4D page table layer is folded at runtime, the p4d_free() should do nothing, the same as in . It seems this bug should cause double-free in efi_call_phys_epilog(), but I don't know how to trigger that code path, so I can't confirm that by testing. Signed-off-by: Andrey Ryabinin Reviewed-by: Kirill A. Shutemov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: stable@vger.kernel.org # 4.17 Fixes: 98219dda2ab5 ("x86/mm: Fold p4d page table layer at runtime") Link: http://lkml.kernel.org/r/20180625102427.15015-1-aryabinin@virtuozzo.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/pgalloc.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/x86/include/asm/pgalloc.h') diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h index ada6410fd2ecf..fbd578daa66e9 100644 --- a/arch/x86/include/asm/pgalloc.h +++ b/arch/x86/include/asm/pgalloc.h @@ -184,6 +184,9 @@ static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr) static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d) { + if (!pgtable_l5_enabled()) + return; + BUG_ON((unsigned long)p4d & (PAGE_SIZE-1)); free_page((unsigned long)p4d); } -- cgit v1.2.3