On Thu, May 30, 2024 at 07:44:12PM -0500, Nathan Lynch via B4 Relay wrote: > From: Nathan Lynch <nath...@linux.ibm.com> > > Smatch warns: > > arch/powerpc/kernel/rtas.c:1932 __do_sys_rtas() warn: potential > spectre issue 'args.args' [r] (local cap) > > The 'nargs' and 'nret' locals come directly from a user-supplied > buffer and are used as indexes into a small stack-based array and as > inputs to copy_to_user() after they are subject to bounds checks. > > Use array_index_nospec() after the bounds checks to clamp these values > for speculative execution. > > Signed-off-by: Nathan Lynch <nath...@linux.ibm.com> > Reported-by: Breno Leitao <lei...@debian.org>
Thanks for working on it. Reviewed-by: Breno Leitao <lei...@debian.org> > + nargs = array_index_nospec(nargs, ARRAY_SIZE(args.args)); > + nret = array_index_nospec(nret, ARRAY_SIZE(args.args) - nargs); On an unrelated note, can nargs and nret are integers and could be eventually negative. Is this a valid use case? Thanks!