All of lore.kernel.org
 help / color / mirror / Atom feed
From: tip-bot for Jiang Biao <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: mingo@kernel.org, hpa@zytor.com, tglx@linutronix.de,
	linux-kernel@vger.kernel.org, jiang.biao2@zte.com.cn
Subject: [tip:x86/pti] x86/pti: Check the return value of pti_user_pagetable_walk_pmd()
Date: Thu, 19 Jul 2018 22:10:21 -0700	[thread overview]
Message-ID: <tip-8c934e01a7ce685d98e970880f5941d79272c654@git.kernel.org> (raw)
In-Reply-To: <1532045192-49622-2-git-send-email-jiang.biao2@zte.com.cn>

Commit-ID:  8c934e01a7ce685d98e970880f5941d79272c654
Gitweb:     https://git.kernel.org/tip/8c934e01a7ce685d98e970880f5941d79272c654
Author:     Jiang Biao <jiang.biao2@zte.com.cn>
AuthorDate: Fri, 20 Jul 2018 08:06:32 +0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 20 Jul 2018 07:07:39 +0200

x86/pti: Check the return value of pti_user_pagetable_walk_pmd()

pti_user_pagetable_walk_pmd() can return NULL, so the return value should
be checked to prevent a NULL pointer dereference.

Add the check and a warning when the PMD allocation fails.

Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: dave.hansen@linux.intel.com
Cc: luto@kernel.org
Cc: hpa@zytor.com
Cc: albcamus@gmail.com
Cc: zhong.weidong@zte.com.cn
Link: https://lkml.kernel.org/r/1532045192-49622-2-git-send-email-jiang.biao2@zte.com.cn

---
 arch/x86/mm/pti.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 001ee6b0619e..bcf35dac1920 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -205,7 +205,7 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address)
 	BUILD_BUG_ON(p4d_large(*p4d) != 0);
 	if (p4d_none(*p4d)) {
 		unsigned long new_pud_page = __get_free_page(gfp);
-		if (!new_pud_page)
+		if (WARN_ON_ONCE(!new_pud_page))
 			return NULL;
 
 		set_p4d(p4d, __p4d(_KERNPG_TABLE | __pa(new_pud_page)));
@@ -219,7 +219,7 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address)
 	}
 	if (pud_none(*pud)) {
 		unsigned long new_pmd_page = __get_free_page(gfp);
-		if (!new_pmd_page)
+		if (WARN_ON_ONCE(!new_pmd_page))
 			return NULL;
 
 		set_pud(pud, __pud(_KERNPG_TABLE | __pa(new_pmd_page)));
@@ -241,9 +241,13 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address)
 static __init pte_t *pti_user_pagetable_walk_pte(unsigned long address)
 {
 	gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO);
-	pmd_t *pmd = pti_user_pagetable_walk_pmd(address);
+	pmd_t *pmd;
 	pte_t *pte;
 
+	pmd = pti_user_pagetable_walk_pmd(address);
+	if (!pmd)
+		return NULL;
+
 	/* We can't do anything sensible if we hit a large mapping. */
 	if (pmd_large(*pmd)) {
 		WARN_ON(1);

  reply	other threads:[~2018-07-20  5:10 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-20  0:06 [PATCH v4 1/2] x86/pti: check the return value of pti_user_pagetable_walk_p4d Jiang Biao
2018-07-20  0:06 ` [PATCH v4 2/2] x86/pti: check the return value of pti_user_pagetable_walk_pmd Jiang Biao
2018-07-20  5:10   ` tip-bot for Jiang Biao [this message]
2018-07-20  5:09 ` [tip:x86/pti] x86/pti: Check the return value of pti_user_pagetable_walk_p4d() tip-bot for Jiang Biao

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=tip-8c934e01a7ce685d98e970880f5941d79272c654@git.kernel.org \
    --to=tipbot@zytor.com \
    --cc=hpa@zytor.com \
    --cc=jiang.biao2@zte.com.cn \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-tip-commits@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=tglx@linutronix.de \
    --subject='Re: [tip:x86/pti] x86/pti: Check the return value of pti_user_pagetable_walk_pmd()' \
    /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

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.