From 9f0cf4adb6aa0bfccf675c938124e68f7f06349d Mon Sep 17 00:00:00 2001 From: Arjan van de Ven <arjan@infradead.org> Date: Sat, 26 Sep 2009 14:33:01 +0200 Subject: x86: Use __builtin_object_size() to validate the buffer size for copy_from_user() gcc (4.x) supports the __builtin_object_size() builtin, which reports the size of an object that a pointer point to, when known at compile time. If the buffer size is not known at compile time, a constant -1 is returned. This patch uses this feature to add a sanity check to copy_from_user(); if the target buffer is known to be smaller than the copy size, the copy is aborted and a WARNing is emitted in memory debug mode. These extra checks compile away when the object size is not known, or if both the buffer size and the copy length are constants. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> LKML-Reference: <20090926143301.2c396b94@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- include/linux/compiler-gcc4.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/compiler-gcc4.h') diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h index 450fa597c94d..a3aef5d55dba 100644 --- a/include/linux/compiler-gcc4.h +++ b/include/linux/compiler-gcc4.h @@ -37,3 +37,5 @@ #define __cold __attribute__((__cold__)) #endif + +#define __compiletime_object_size(obj) __builtin_object_size(obj, 0) -- cgit v1.2.3-70-g09d2