On Wed, Jun 23, 2021 at 08:39:01AM +1000, Stephen Rothwell wrote: > Hi all, > > After merging the kspp-gustavo tree, today's linux-next build (powerpc > ppc64_defconfig) produced this warning: > > In file included from fs/btrfs/ctree.h:9, > from fs/btrfs/struct-funcs.c:8: > fs/btrfs/struct-funcs.c: In function 'btrfs_get_token_16': > fs/btrfs/struct-funcs.c:80:46: warning: array subscript 1 is above array bounds of 'struct page *[1]' [-Warray-bounds] > 80 | token->kaddr = page_address(token->eb->pages[idx + 1]); \ > | ~~~~~~~~~~~~~~~~^~~~~~~~~ The warning is correct, on powerpc and 64k pages the array has only 1 item, ie. only index 0 is valid. The overflow won't happen in practice though because of previous branch that would happen in 100% cases. The code handles when some bytes cross 2 pages but on 64k pages it's all just one page. To allow the warning to be enabled globally we'll fix it, I'll let Gustavo know once it's done.
