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List:       git-commits-head
Subject:    x86/pti: Filter at vma->vm_page_prot population
From:       "Linux Kernel Mailing List" <linux-kernel () vger ! kernel ! org>
Date:       2018-04-29 17:18:06
Message-ID: 20180429171806.CC71822182 () pdx-korg-gitolite-1 ! ci ! codeaurora ! org
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Web:        https://git.kernel.org/torvalds/c/316d097c4cd4e7f2ef50c40cff2db266593c4ec4
                
Commit:     316d097c4cd4e7f2ef50c40cff2db266593c4ec4
Parent:     b7c21bc56fbedf4a61b628c6b11e0d7048746cc1
Refname:    refs/heads/master
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Fri Apr 20 15:20:28 2018 -0700
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed Apr 25 11:02:51 2018 +0200

    x86/pti: Filter at vma->vm_page_prot population
    
    commit ce9962bf7e22bb3891655c349faff618922d4a73
    
    0day reported warnings at boot on 32-bit systems without NX support:
    
    attempted to set unsupported pgprot: 8000000000000025 bits: 8000000000000000 \
supported: 7fffffffffffffff  WARNING: CPU: 0 PID: 1 at
    arch/x86/include/asm/pgtable.h:540 handle_mm_fault+0xfc1/0xfe0:
     check_pgprot at arch/x86/include/asm/pgtable.h:535
     (inlined by) pfn_pte at arch/x86/include/asm/pgtable.h:549
     (inlined by) do_anonymous_page at mm/memory.c:3169
     (inlined by) handle_pte_fault at mm/memory.c:3961
     (inlined by) __handle_mm_fault at mm/memory.c:4087
     (inlined by) handle_mm_fault at mm/memory.c:4124
    
    The problem is that due to the recent commit which removed auto-massaging
    of page protections, filtering page permissions at PTE creation time is not
    longer done, so vma->vm_page_prot is passed unfiltered to PTE creation.
    
    Filter the page protections before they are installed in vma->vm_page_prot.
    
    Fixes: fb43d6cb91 ("x86/mm: Do not auto-massage page protections")
    Reported-by: Fengguang Wu <fengguang.wu@intel.com>
    Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: Ingo Molnar <mingo@kernel.org>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Juergen Gross <jgross@suse.com>
    Cc: Kees Cook <keescook@google.com>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: David Woodhouse <dwmw2@infradead.org>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: linux-mm@kvack.org
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Nadav Amit <namit@vmware.com>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Arjan van de Ven <arjan@linux.intel.com>
    Link: https://lkml.kernel.org/r/20180420222028.99D72858@viggo.jf.intel.com
---
 arch/x86/Kconfig               |  4 ++++
 arch/x86/include/asm/pgtable.h |  5 +++++
 mm/mmap.c                      | 11 ++++++++++-
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 00fcf81f2c56..c07f492b871a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -52,6 +52,7 @@ config X86
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FAST_MULTIPLIER
+	select ARCH_HAS_FILTER_PGPROT
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_KCOV			if X86_64
@@ -273,6 +274,9 @@ config ARCH_HAS_CPU_RELAX
 config ARCH_HAS_CACHE_LINE_SIZE
 	def_bool y
 
+config ARCH_HAS_FILTER_PGPROT
+	def_bool y
+
 config HAVE_SETUP_PER_CPU_AREA
 	def_bool y
 
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 5f49b4ff0c24..f1633de5a675 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -601,6 +601,11 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t \
newprot)  
 #define canon_pgprot(p) __pgprot(massage_pgprot(p))
 
+static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
+{
+	return canon_pgprot(prot);
+}
+
 static inline int is_new_memtype_allowed(u64 paddr, unsigned long size,
 					 enum page_cache_mode pcm,
 					 enum page_cache_mode new_pcm)
diff --git a/mm/mmap.c b/mm/mmap.c
index 188f195883b9..9d5968d1e8e3 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -100,11 +100,20 @@ pgprot_t protection_map[16] __ro_after_init = {
 	__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
 };
 
+#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
+static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
+{
+	return prot;
+}
+#endif
+
 pgprot_t vm_get_page_prot(unsigned long vm_flags)
 {
-	return __pgprot(pgprot_val(protection_map[vm_flags &
+	pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
 				(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
 			pgprot_val(arch_vm_get_page_prot(vm_flags)));
+
+	return arch_filter_pgprot(ret);
 }
 EXPORT_SYMBOL(vm_get_page_prot);
 
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