From: Andrey Ryabinin Date: Wed, 7 May 2014 07:07:25 +0000 (+0100) Subject: ARM: 8051/1: put_user: fix possible data corruption in put_user X-Git-Tag: v3.2.61~112 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=f85743e62e15955caa5da907f5a2b02b351722d3 ARM: 8051/1: put_user: fix possible data corruption in put_user commit 537094b64b229bf3ad146042f83e74cf6abe59df upstream. According to arm procedure call standart r2 register is call-cloberred. So after the result of x expression was put into r2 any following function call in p may overwrite r2. To fix this, the result of p expression must be saved to the temporary variable before the assigment x expression to __r2. Signed-off-by: Andrey Ryabinin Reviewed-by: Nicolas Pitre Signed-off-by: Russell King Signed-off-by: Ben Hutchings --- diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 292c3f88f01d..18a285892bc4 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -158,8 +158,9 @@ extern int __put_user_8(void *, unsigned long long); #define put_user(x,p) \ ({ \ unsigned long __limit = current_thread_info()->addr_limit - 1; \ + const typeof(*(p)) __user *__tmp_p = (p); \ register const typeof(*(p)) __r2 asm("r2") = (x); \ - register const typeof(*(p)) __user *__p asm("r0") = (p);\ + register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \ register unsigned long __l asm("r1") = __limit; \ register int __e asm("r0"); \ switch (sizeof(*(__p))) { \