The patch titled
Subject: x86/kasan: instrument user memory access API
has been added to the -mm tree. Its filename is
x86-kasan-instrument-user-memory-access-api.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/x86-kasan-instrument-user-memory-access-api.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/x86-kasan-instrument-user-memory-access-api.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Subject: x86/kasan: instrument user memory access API
Exchange between user and kernel memory is coded in assembly language.
Which means that such accesses won't be spotted by KASAN as a compiler
instruments only C code.
Add explicit KASAN checks to user memory access API to ensure that
userspace writes to (or reads from) a valid kernel memory.
Note: Unlike others strncpy_from_user() is written mostly in C and KASAN
sees memory accesses in it. However, it makes sense to add explicit check
for all @count bytes that *potentially* could be written to the kernel.
Link: http://lkml.kernel.org/r/1462538722-1574-4-git-send-email-aryabinin@xxxxxxxxxxxxx
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/uaccess.h | 5 +++++
arch/x86/include/asm/uaccess_64.h | 7 +++++++
lib/strncpy_from_user.c | 2 ++
3 files changed, 14 insertions(+)
diff -puN arch/x86/include/asm/uaccess.h~x86-kasan-instrument-user-memory-access-api arch/x86/include/asm/uaccess.h
--- a/arch/x86/include/asm/uaccess.h~x86-kasan-instrument-user-memory-access-api
+++ a/arch/x86/include/asm/uaccess.h
@@ -5,6 +5,7 @@
*/
#include <linux/errno.h>
#include <linux/compiler.h>
+#include <linux/kasan-checks.h>
#include <linux/thread_info.h>
#include <linux/string.h>
#include <asm/asm.h>
@@ -713,6 +714,8 @@ copy_from_user(void *to, const void __us
might_fault();
+ kasan_check_write(to, n);
+
/*
* While we would like to have the compiler do the checking for us
* even in the non-constant size case, any false positives there are
@@ -746,6 +749,8 @@ copy_to_user(void __user *to, const void
{
int sz = __compiletime_object_size(from);
+ kasan_check_read(from, n);
+
might_fault();
/* See the comment in copy_from_user() above. */
diff -puN arch/x86/include/asm/uaccess_64.h~x86-kasan-instrument-user-memory-access-api arch/x86/include/asm/uaccess_64.h
--- a/arch/x86/include/asm/uaccess_64.h~x86-kasan-instrument-user-memory-access-api
+++ a/arch/x86/include/asm/uaccess_64.h
@@ -7,6 +7,7 @@
#include <linux/compiler.h>
#include <linux/errno.h>
#include <linux/lockdep.h>
+#include <linux/kasan-checks.h>
#include <asm/alternative.h>
#include <asm/cpufeatures.h>
#include <asm/page.h>
@@ -109,6 +110,7 @@ static __always_inline __must_check
int __copy_from_user(void *dst, const void __user *src, unsigned size)
{
might_fault();
+ kasan_check_write(dst, size);
return __copy_from_user_nocheck(dst, src, size);
}
@@ -175,6 +177,7 @@ static __always_inline __must_check
int __copy_to_user(void __user *dst, const void *src, unsigned size)
{
might_fault();
+ kasan_check_read(src, size);
return __copy_to_user_nocheck(dst, src, size);
}
@@ -242,12 +245,14 @@ int __copy_in_user(void __user *dst, con
static __must_check __always_inline int
__copy_from_user_inatomic(void *dst, const void __user *src, unsigned size)
{
+ kasan_check_write(dst, size);
return __copy_from_user_nocheck(dst, src, size);
}
static __must_check __always_inline int
__copy_to_user_inatomic(void __user *dst, const void *src, unsigned size)
{
+ kasan_check_read(src, size);
return __copy_to_user_nocheck(dst, src, size);
}
@@ -258,6 +263,7 @@ static inline int
__copy_from_user_nocache(void *dst, const void __user *src, unsigned size)
{
might_fault();
+ kasan_check_write(dst, size);
return __copy_user_nocache(dst, src, size, 1);
}
@@ -265,6 +271,7 @@ static inline int
__copy_from_user_inatomic_nocache(void *dst, const void __user *src,
unsigned size)
{
+ kasan_check_write(dst, size);
return __copy_user_nocache(dst, src, size, 0);
}
diff -puN lib/strncpy_from_user.c~x86-kasan-instrument-user-memory-access-api lib/strncpy_from_user.c
--- a/lib/strncpy_from_user.c~x86-kasan-instrument-user-memory-access-api
+++ a/lib/strncpy_from_user.c
@@ -1,5 +1,6 @@
#include <linux/compiler.h>
#include <linux/export.h>
+#include <linux/kasan-checks.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/errno.h>
@@ -103,6 +104,7 @@ long strncpy_from_user(char *dst, const
if (unlikely(count <= 0))
return 0;
+ kasan_check_write(dst, count);
max_addr = user_addr_max();
src_addr = (unsigned long)src;
if (likely(src_addr < max_addr)) {
_
Patches currently in -mm which might be from aryabinin@xxxxxxxxxxxxx are
mm-kasan-print-name-of-mem-caller-in-report.patch
mm-kasan-add-api-to-check-memory-regions.patch
x86-kasan-instrument-user-memory-access-api.patch
kasan-tests-add-tests-for-user-memory-access-functions.patch
--
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