| From d80ae83f1f932ab7af47b54d0d3bef4f4dba489f Mon Sep 17 00:00:00 2001 |
| From: Christophe Leroy <christophe.leroy@c-s.fr> |
| Date: Tue, 14 Jan 2020 08:13:09 +0000 |
| Subject: powerpc/ptdump: Fix W+X verification |
| |
| From: Christophe Leroy <christophe.leroy@c-s.fr> |
| |
| 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 <christophe.leroy@c-s.fr> |
| Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
| Link: https://lore.kernel.org/r/0d894839fdbb19070f0e1e4140363be4f2bb62fc.1578989540.git.christophe.leroy@c-s.fr |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/powerpc/mm/ptdump/ptdump.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| --- 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 *s |
| |
| 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", |
