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authorAlexander Potapenko <glider@google.com>2022-10-24 23:21:43 +0200
committerAndrew Morton <akpm@linux-foundation.org>2022-10-28 13:37:23 -0700
commit59c8a02e24894e75639bcecc3cb1e768a2792220 (patch)
tree0a1d7eb39339b0bf5f92d857d252a226435eb7da
parent921757bc9b611efc483a548b86769934384e9c79 (diff)
downloadlinux-59c8a02e24894e75639bcecc3cb1e768a2792220.tar.bz2
x86: asm: make sure __put_user_size() evaluates pointer once
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. Link: https://lkml.kernel.org/r/20221024212144.2852069-4-glider@google.com Fixes: 888f84a6da4d ("x86: asm: instrument usercopy in get_user() and put_user()") Signed-off-by: Alexander Potapenko <glider@google.com> Reported-by: youling257 <youling257@gmail.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--arch/x86/include/asm/uaccess.h13
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 8bc614cfe21b..1cc756eafa44 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