On Wed, Nov 13, 2013 at 12:57:13PM -0800, H. Peter Anvin wrote: > On 11/13/2013 10:39 AM, Kees Cook wrote: > > Hi Guenter, > > > > On Fri, Apr 12, 2013 at 07:49:08PM -0700, Guenter Roeck wrote: > >> __builtin_object_size is known to be broken on gcc 4.6+. > >> See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48880 for details. > >> > >> This causes unnecssary build warnings and errors such as > >> > >> In function 'copy_from_user', inlined from 'sb16_copy_from_user' > >> at sound/oss/sb_audio.c:878:22: > >> arch/x86/include/asm/uaccess_32.h:211:26: error: call to > >> 'copy_from_user_overflow' > >> declared with attribute error: copy_from_user() buffer size is not > >> provably correct > >> make[3]: [sound/oss/sb_audio.o] Error 1 (ignored) > >> > >> Disable it where broken. > > > > Is there an alternative? This means that things like > > DEBUG_STRICT_USER_COPY_CHECKS are being rendered useless. I don't think > > this is _always_ broken, just under certain situations, right? > > > > It would be one thing to block it for, say, gcc 4.6 and 4.7 only, but > without an upper cap I don't think this is at all okay. > Also please have a look into https://lkml.org/lkml/2013/10/21/52. That patch has been accepted (3df7b41aa5e); maybe above commit (2fb0815c9) is now unnecessary and can be reverted.
I don't know about parisc (Jan was concerned about that), but at least on x86 I don't see above warning anymore after reverting my patch. Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
