On Fri, 30 Sep 2011 15:32:55 +1000 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote: > Hi Andrew, > > After merging the akpm tree, today's linux-next build (x86_64 allmodconfig) > failed like this: > > In file included from arch/x86/include/asm/uaccess.h:575:0, > from include/net/checksum.h:25, > from include/linux/skbuff.h:28, > from include/linux/icmpv6.h:82, > from net/compat.c:19: > In function 'copy_from_user', > inlined from 'compat_sys_socketcall' at net/compat.c:793:20: > arch/x86/include/asm/uaccess_64.h:64:26: error: call to 'copy_from_user_overflow' declared with attribute error: copy_from_user() buffer size is not provably correct > > Caused by commit 15e19cbbbf2a ("x86: implement strict user copy checks > for x86_64") when built with gcc 4.6.0. This does not fail when built > with 4.5.2. This: extern void copy_from_user_overflow(void) #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS __compiletime_error("copy_from_user() buffer size is not provably correct") #else __compiletime_warning("copy_from_user() buffer size is not provably correct") #endif presumably CONFIG_DEBUG_STRICT_USER_COPY_CHECKS=y, so it's doing what we asked it to do. > The problem here is that the length parameter to copy_from_user() is > obtained by indexing into an array of sizes. Making the array const > does not help (obviously, since the index is not known at compile time > anyway). > > Maybe I need a newer compiler. For today I have gone back to my 4.5.2 > compiler. That patch is a PITA. I've been waiting for some saviour to come along and fix all the warnings it emits before proceeding with it. As I am apparently saviourless I shall hide that patch from the mm->linux-next drop, so only I get to suffer its effects. -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html