All of lore.kernel.org
 help / color / mirror / Atom feed
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: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.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


WARNING: multiple messages have this Message-ID (diff)
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


             reply	other threads:[~2020-01-14  8:13 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-14  8:13 Christophe Leroy [this message]
2020-01-14  8:13 ` [PATCH] powerpc/ptdump: fix W+X verification Christophe Leroy
2020-01-29  5:17 ` Michael Ellerman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=0d894839fdbb19070f0e1e4140363be4f2bb62fc.1578989540.git.christophe.leroy@c-s.fr \
    --to=christophe.leroy@c-s.fr \
    --cc=benh@kernel.crashing.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mpe@ellerman.id.au \
    --cc=paulus@samba.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.