@@ -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
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@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86@kernel.org Reported-by: youling257 <youling257@gmail.com> Signed-off-by: Alexander Potapenko <glider@google.com> 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(-)