From 796085dbe323d82e511105690bf5d15650bb342e Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Tue, 14 Jan 2020 08:13:09 +0000 Subject: [PATCH] powerpc/ptdump: Fix W+X verification commit d80ae83f1f932ab7af47b54d0d3bef4f4dba489f upstream. Verification cannot rely on simple bit checking because on some platforms PAGE_RW is 0, checking that a page is not W means checking that PAGE_RO is set instead of checking that PAGE_RW is not set. Use pte helpers instead of checking bits. Fixes: 453d87f6a8ae ("powerpc/mm: Warn if W+X pages found on boot") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/0d894839fdbb19070f0e1e4140363be4f2bb62fc.1578989540.git.christophe.leroy@c-s.fr Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/mm/ptdump/ptdump.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c index 2f9ddc2..c732051 100644 --- a/arch/powerpc/mm/ptdump/ptdump.c +++ b/arch/powerpc/mm/ptdump/ptdump.c @@ -173,10 +173,12 @@ static void dump_addr(struct pg_state *st, unsigned long addr) static void note_prot_wx(struct pg_state *st, unsigned long addr) { + pte_t pte = __pte(st->current_flags); + if (!IS_ENABLED(CONFIG_PPC_DEBUG_WX) || !st->check_wx) return; - if (!((st->current_flags & pgprot_val(PAGE_KERNEL_X)) == pgprot_val(PAGE_KERNEL_X))) + if (!pte_write(pte) || !pte_exec(pte)) return; WARN_ONCE(1, "powerpc/mm: Found insecure W+X mapping at address %p/%pS\n", -- 2.7.4