tree 2045a8fa0b207a8adb288eb144c593db7d1f2f0b
parent 704daf55c7297e727021063cb5d8ba1c55b84426
author Arjan van de Ven <arjan@infradead.org> 1253968381 +0200
committer Ingo Molnar <mingo@elte.hu> 1253975141 +0200

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>