From 4a3127693001c61a21d1ce680db6340623f52e93 Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Wed, 30 Sep 2009 13:05:23 +0200 Subject: x86: Turn the copy_from_user check into an (optional) compile time warning A previous patch added the buffer size check to copy_from_user(). One of the things learned from analyzing the result of the previous patch is that in general, gcc is really good at proving that the code contains sufficient security checks to not need to do a runtime check. But that for those cases where gcc could not prove this, there was a relatively high percentage of real security issues. This patch turns the case of "gcc cannot prove" into a compile time warning, as long as a sufficiently new gcc is in use that supports this. The objective is that these warnings will trigger developers checking new cases out before a security hole enters a linux kernel release. Signed-off-by: Arjan van de Ven Cc: Linus Torvalds Cc: "David S. Miller" Cc: James Morris Cc: Jan Beulich LKML-Reference: <20090930130523.348ae6c4@infradead.org> Signed-off-by: Ingo Molnar --- arch/x86/lib/usercopy_32.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/x86/lib') diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c index 8498684e45b0..e218d5df85ff 100644 --- a/arch/x86/lib/usercopy_32.c +++ b/arch/x86/lib/usercopy_32.c @@ -883,3 +883,9 @@ _copy_from_user(void *to, const void __user *from, unsigned long n) return n; } EXPORT_SYMBOL(_copy_from_user); + +void copy_from_user_overflow(void) +{ + WARN(1, "Buffer overflow detected!\n"); +} +EXPORT_SYMBOL(copy_from_user_overflow); -- cgit v1.2.3