From: Albert van der Linde <ali...@google.com>
To test fault-tolerance of user memory acceses in x86, add support for
fault injection.
Make both put_user() and get_user() fail with -EFAULT, and clear_user()
fail by not clearing any bytes.
Reviewed-by: Akinobu Mita <akinobu.m...@gmail.com>
Reviewed-by: Alexander Potapenko <gli...@google.com>
Signed-off-by: Albert van der Linde <ali...@google.com>
Signed-off-by: Alexander Potapenko <gli...@google.com>
---
v2:
- no significant changes
v3:
- no changes
v4:
- instrument the new out-of-line implementations of get_user()/put_user()
- fix a minor checkpatch warning in the inline assembly
v5:
- rebase after another change to put_user()
- fix an issue reported by kernel test robot <l...@intel.com>
---
---
arch/x86/include/asm/uaccess.h | 38 +++++++++++++++++++++-------------
arch/x86/lib/usercopy_64.c | 3 +++
2 files changed, 27 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index c9fa7be3df82..036467b850f8 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -5,6 +5,7 @@
* User space memory access functions
*/
#include <linux/compiler.h>
+#include <linux/fault-inject-usercopy.h>
#include <linux/kasan-checks.h>
#include <linux/string.h>
#include <asm/asm.h>
@@ -126,11 +127,16 @@ extern int __get_user_bad(void);
int __ret_gu; \
register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \
__chk_user_ptr(ptr); \
- asm volatile("call __" #fn "_%P4" \
- : "=a" (__ret_gu), "=r" (__val_gu), \
- ASM_CALL_CONSTRAINT \
- : "0" (ptr), "i" (sizeof(*(ptr)))); \
- (x) = (__force __typeof__(*(ptr))) __val_gu; \
+ if (should_fail_usercopy()) { \
+ (x) = 0; \
+ __ret_gu = -EFAULT; \
+ } else { \
+ asm volatile("call __" #fn "_%P4" \
+ : "=a" (__ret_gu), "=r" (__val_gu), \
+ ASM_CALL_CONSTRAINT \
+ : "0" (ptr), "i" (sizeof(*(ptr)))); \
+ (x) = (__force __typeof__(*(ptr))) __val_gu; \
+ } \
__builtin_expect(__ret_gu, 0); \
})
@@ -220,15 +226,19 @@ extern void __put_user_nocheck_8(void);
void __user *__ptr_pu; \
register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \
__chk_user_ptr(ptr); \
- __ptr_pu = (ptr); \
- __val_pu = (x); \
- asm volatile("call __" #fn "_%P[size]" \
- : "=c" (__ret_pu), \
- ASM_CALL_CONSTRAINT \
- : "0" (__ptr_pu), \
- "r" (__val_pu), \
- [size] "i" (sizeof(*(ptr))) \
- :"ebx"); \
+ if (unlikely(should_fail_usercopy())) { \
+ __ret_pu = -EFAULT; \
+ } else { \
+ __ptr_pu = (ptr); \
+ __val_pu = (x); \
+ asm volatile("call __" #fn "_%P[size]" \
+ : "=c" (__ret_pu), \
+ ASM_CALL_CONSTRAINT \
+ : "0" (__ptr_pu), \
+ "r" (__val_pu), \
+ [size] "i" (sizeof(*(ptr))) \
+ : "ebx"); \
+ } \
__builtin_expect(__ret_pu, 0); \
})
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index 508c81e97ab1..5617b3864586 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -7,6 +7,7 @@
* Copyright 2002 Andi Kleen <a...@suse.de>
*/
#include <linux/export.h>
+#include <linux/fault-inject-usercopy.h>
#include <linux/uaccess.h>
#include <linux/highmem.h>
@@ -50,6 +51,8 @@ EXPORT_SYMBOL(__clear_user);
unsigned long clear_user(void __user *to, unsigned long n)
{
+ if (should_fail_usercopy())
+ return n;
if (access_ok(to, n))
return __clear_user(to, n);
return n;
--
2.29.1.341.ge80a0c044ae-goog
