From: Albert van der Linde <alinde@xxxxxxxxxx> 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.mita@xxxxxxxxx> Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx> Signed-off-by: Albert van der Linde <alinde@xxxxxxxxxx> Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> --- 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 --- --- arch/x86/include/asm/uaccess.h | 36 ++++++++++++++++++++++------------ arch/x86/lib/usercopy_64.c | 3 +++ 2 files changed, 26 insertions(+), 13 deletions(-) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index f13659523108..7041ebc48b75 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); \ }) @@ -213,14 +219,18 @@ extern void __put_user_nocheck_8(void); int __ret_pu; \ register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \ __chk_user_ptr(ptr); \ - __val_pu = (x); \ - asm volatile("call __" #fn "_%P[size]" \ - : "=c" (__ret_pu), \ - ASM_CALL_CONSTRAINT \ - : "0" (ptr), \ - "r" (__val_pu), \ - [size] "i" (sizeof(*(ptr))) \ - :"ebx"); \ + if (unlikely(should_fail_usercopy())) { \ + __ret_pu = -EFAULT; \ + } else { \ + __val_pu = (x); \ + asm volatile("call __" #fn "_%P[size]" \ + : "=c" (__ret_pu), \ + ASM_CALL_CONSTRAINT \ + : "0" (ptr), \ + "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 <ak@xxxxxxx> */ #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; -- 2.29.0.rc2.309.g374f81d7ae-goog