From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] powerpc/ptdump: fix W+X verification
Date: Tue, 14 Jan 2020 08:13:09 +0000 (UTC) [thread overview]
Message-ID: <0d894839fdbb19070f0e1e4140363be4f2bb62fc.1578989540.git.christophe.leroy@c-s.fr> (raw)
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.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Fixes: 453d87f6a8ae ("powerpc/mm: Warn if W+X pages found on boot")
---
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 4af0d5d9589e..206156255247 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -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",
--
2.13.3
next reply other threads:[~2020-01-14 8:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 8:13 Christophe Leroy [this message]
2020-01-29 5:17 ` [PATCH] powerpc/ptdump: fix W+X verification Michael Ellerman
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