User access macros must ensure their arguments are evaluated only once
if they are used more than once in the macro body. Adding
instrument_put_user() to __put_user_size() resulted in double evaluation
of the `ptr` argument, which led to correctness issues when performing
e.g. unsafe_put_user(..., p++, ...).
To fix those issues, evaluate the `ptr` argument of __put_user_size()
at the beginning of the macro.
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Reported-by: youling257 <youling257@xxxxxxxxx>
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Fixes: 888f84a6da4d ("x86: asm: instrument usercopy in get_user() and put_user()")
---
arch/x86/include/asm/uaccess.h | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 8bc614cfe21b9..1cc756eafa447 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -254,24 +254,25 @@ extern void __put_user_nocheck_8(void);
#define __put_user_size(x, ptr, size, label) \
do { \
__typeof__(*(ptr)) __x = (x); /* eval x once */ \
- __chk_user_ptr(ptr); \
+ __typeof__(ptr) __ptr = (ptr); /* eval ptr once */ \
+ __chk_user_ptr(__ptr); \
switch (size) { \
case 1: \
- __put_user_goto(__x, ptr, "b", "iq", label); \
+ __put_user_goto(__x, __ptr, "b", "iq", label); \
break; \
case 2: \
- __put_user_goto(__x, ptr, "w", "ir", label); \
+ __put_user_goto(__x, __ptr, "w", "ir", label); \
break; \
case 4: \
- __put_user_goto(__x, ptr, "l", "ir", label); \
+ __put_user_goto(__x, __ptr, "l", "ir", label); \
break; \
case 8: \
- __put_user_goto_u64(__x, ptr, label); \
+ __put_user_goto_u64(__x, __ptr, label); \
break; \
default: \
__put_user_bad(); \
} \
- instrument_put_user(__x, ptr, size); \
+ instrument_put_user(__x, __ptr, size); \
} while (0)
#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
--
2.38.0.135.g90850a2211-goog
