lkml.org 
[lkml]   [2018]   [Sep]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.18 095/235] x86/pti: Check the return value of pti_user_pagetable_walk_pmd()
Date
4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jiang Biao <jiang.biao2@zte.com.cn>

[ Upstream commit 8c934e01a7ce685d98e970880f5941d79272c654 ]

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
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/mm/pti.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -206,7 +206,7 @@ static pmd_t *pti_user_pagetable_walk_pm
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)));
@@ -220,7 +220,7 @@ static pmd_t *pti_user_pagetable_walk_pm
}
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)));
@@ -242,9 +242,13 @@ static pmd_t *pti_user_pagetable_walk_pm
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);

\
 
 \ /
  Last update: 2018-09-24 14:33    [W:0.984 / U:4.764 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site