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.157898954... 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",