On Fri, 7 Feb 2014, Peter Zijlstra wrote: > There's further problems where things like memset() can write outside > the specified address range. Examples are memset() using single > instructions to wipe entire cachelines and then 'restoring' the tail > bit.
If memset (or any C library function) modifies bytes it's not permitted to modify in the abstract machine, that's a simple bug and should be reported as usual. We've made GCC follow that part of the memory model by default (so a store to a non-bit-field structure field doesn't do a read-modify-write to a word containing another field, for example) and I think it's pretty obvious that glibc should do so as well. (Of course, memset is not an atomic operation, and you need to allow for that if you use it on an _Atomic object - which is I think valid, unless the object is also volatile, but perhaps ill-advised.) -- Joseph S. Myers jos...@codesourcery.com -- 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/
