Commit d80ae83f authored Jan 14, 2020 by Christophe Leroy Committed by Michael Ellerman Jan 23, 2020

powerpc/ptdump: Fix W+X verification



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: 453d87f6 ("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

parent e26ad936

arch/powerpc/mm/ptdump/ptdump.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -175,10 +175,12 @@ 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",

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