From: Eric W. Biederman Date: Thu, 23 Mar 2006 10:59:35 +0000 (-0800) Subject: [PATCH] i386: Add a temporary to make put_user more type safe X-Git-Tag: v2.6.17-rc1~1104 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=30e931d4092713cecd6b8c2fd70f268efaa6e428;p=linux-2.6 [PATCH] i386: Add a temporary to make put_user more type safe In some code I am developing I had occasion to change the type of a variable. This made the value put_user was putting to user space wrong. But the code continued to build cleanly without errors. Introducing a temporary fixes this problem and at least with gcc-3.3.5 does not cause gcc any problems with optimizing out the temporary. gcc-4.x using SSA internally ought to be even better at optimizing out temporaries, so I don't expect a temporary to become a problem. Especially because in all correct cases the types on both sides of the assignment to the temporary are the same. Signed-off-by: Eric W. Biederman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/asm-i386/uaccess.h b/include/asm-i386/uaccess.h index 3f1337c342..371457b1ce 100644 --- a/include/asm-i386/uaccess.h +++ b/include/asm-i386/uaccess.h @@ -197,13 +197,15 @@ extern void __put_user_8(void); #define put_user(x,ptr) \ ({ int __ret_pu; \ + __typeof__(*(ptr)) __pu_val; \ __chk_user_ptr(ptr); \ + __pu_val = x; \ switch(sizeof(*(ptr))) { \ - case 1: __put_user_1(x, ptr); break; \ - case 2: __put_user_2(x, ptr); break; \ - case 4: __put_user_4(x, ptr); break; \ - case 8: __put_user_8(x, ptr); break; \ - default:__put_user_X(x, ptr); break; \ + case 1: __put_user_1(__pu_val, ptr); break; \ + case 2: __put_user_2(__pu_val, ptr); break; \ + case 4: __put_user_4(__pu_val, ptr); break; \ + case 8: __put_user_8(__pu_val, ptr); break; \ + default:__put_user_X(__pu_val, ptr); break; \ } \ __ret_pu; \ })