On Wed, May 11, 2022 at 03:16:47PM -0700, Jakub Kicinski wrote: > On Tue, 10 May 2022 13:57:29 -0700 Kees Cook wrote: > > Clang randstruct gets upset when it sees struct addresspace (which is > > randomized) being assigned to a struct page (which is not randomized): > > > > drivers/net/ethernet/sun/niu.c:3385:12: error: casting from randomized structure pointer type 'struct address_space *' to 'struct page *' > > *link = (struct page *) page->mapping; > > ^ > > > > It looks like niu.c is looking for an in-line place to chain its allocated > > pages together and is overloading the "mapping" member, as it is unused. > > This is very non-standard, and is expected to be cleaned up in the > > future[1], but there is no "correct" way to handle it today. > > > > No meaningful machine code changes result after this change, and source > > readability is improved. > > > > Drop the randstruct exception now that there is no "confusing" cross-type > > assignment. > > > > [1] https://lore.kernel.org/lkml/YnqgjVoMDu5v9PNG@xxxxxxxxxxxxxxxxxxxx/ > > > > Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> > > Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> > > Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> > > Cc: Jakub Kicinski <kuba@xxxxxxxxxx> > > Cc: Paolo Abeni <pabeni@xxxxxxxxxx> > > Cc: Du Cheng <ducheng2@xxxxxxxxx> > > Cc: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> > > Cc: Vlastimil Babka <vbabka@xxxxxxx> > > Cc: William Kucharski <william.kucharski@xxxxxxxxxx> > > Cc: Arnd Bergmann <arnd@xxxxxxxx> > > Cc: Nathan Chancellor <nathan@xxxxxxxxxx> > > Cc: netdev@xxxxxxxxxxxxxxx > > Cc: linux-mm@xxxxxxxxx > > Cc: linux-hardening@xxxxxxxxxxxxxxx > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > I presume you prefer to take this one via your tree too, so: Yeah, that's easiest for the exception removals. > Acked-by: Jakub Kicinski <kuba@xxxxxxxxxx> Thanks! -- Kees Cook
