From: Joerg Roedel <joro@8bytes.org>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Juergen Gross <jgross@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Brian Gerst <brgerst@gmail.com>,
David Laight <David.Laight@aculab.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Eduardo Valentin <eduval@amazon.com>,
Greg KH <gregkh@linuxfoundation.org>,
Will Deacon <will.deacon@arm.com>,
aliguori@amazon.com, daniel.gruss@iaik.tugraz.at,
hughd@google.com, keescook@google.com,
Andrea Arcangeli <aarcange@redhat.com>,
Waiman Long <llong@redhat.com>, Pavel Machek <pavel@ucw.cz>,
"David H . Gutteridge" <dhgutteridge@sympatico.ca>,
jroedel@suse.de, Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
joro@8bytes.org
Subject: [PATCH 3/3] x86/kexec: Allocate 8k PGDs for PTI
Date: Wed, 25 Jul 2018 17:48:03 +0200 [thread overview]
Message-ID: <1532533683-5988-4-git-send-email-joro@8bytes.org> (raw)
In-Reply-To: <1532533683-5988-1-git-send-email-joro@8bytes.org>
From: Joerg Roedel <jroedel@suse.de>
Fuzzing the PTI-x86-32 code with trinity showed unhandled
kernel paging request oops-messages that looked a lot like
silent data corruption.
Lot's of debugging and testing lead to the kexec-32bit code,
which is still allocating 4k PGDs when PTI is enabled. But
since it uses native_set_pud() to build the page-table, it
will unevitably call into __pti_set_user_pgtbl(), which
writes beyond the allocated 4k page.
Use PGD_ALLOCATION_ORDER to allocate PGDs in the kexec code
to fix the issue.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/kernel/machine_kexec_32.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index d1ab07e..5409c28 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -56,7 +56,7 @@ static void load_segments(void)
static void machine_kexec_free_page_tables(struct kimage *image)
{
- free_page((unsigned long)image->arch.pgd);
+ free_pages((unsigned long)image->arch.pgd, PGD_ALLOCATION_ORDER);
image->arch.pgd = NULL;
#ifdef CONFIG_X86_PAE
free_page((unsigned long)image->arch.pmd0);
@@ -72,7 +72,8 @@ static void machine_kexec_free_page_tables(struct kimage *image)
static int machine_kexec_alloc_page_tables(struct kimage *image)
{
- image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);
+ image->arch.pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+ PGD_ALLOCATION_ORDER);
#ifdef CONFIG_X86_PAE
image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
--
2.7.4
next prev parent reply other threads:[~2018-07-25 15:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-25 15:48 [PATCH 0/3] PTI x86-32 Updates and Fixes Joerg Roedel
2018-07-25 15:48 ` [PATCH 1/3] x86/mm: Remove in_nmi() warning from vmalloc_fault() Joerg Roedel
2018-07-30 11:57 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-25 15:48 ` [PATCH 2/3] Revert "perf/core: Make sure the ring-buffer is mapped in all page-tables" Joerg Roedel
2018-07-30 11:58 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-25 15:48 ` Joerg Roedel [this message]
2018-07-30 11:58 ` [tip:x86/pti] x86/kexec: Allocate 8k PGDs for PTI tip-bot for Joerg Roedel
2018-07-30 7:08 ` [PATCH 0/3] PTI x86-32 Updates and Fixes David H. Gutteridge
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