Messages in this thread | | | Date | Wed, 28 Dec 2022 06:44:08 -0800 | From | Guenter Roeck <> | Subject | Re: Linux 6.2-rc1 |
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On Tue, Dec 27, 2022 at 07:40:30PM -0800, Kees Cook wrote: > On December 26, 2022 9:52:12 PM PST, Guenter Roeck <linux@roeck-us.net> wrote: > >On Mon, Dec 26, 2022 at 05:32:28PM -0800, Kees Cook wrote: > >> On December 26, 2022 4:29:41 PM PST, Guenter Roeck <linux@roeck-us.net> wrote: > >> >On Mon, Dec 26, 2022 at 01:03:59PM -0800, Kees Cook wrote: > >> >> On December 26, 2022 12:56:29 PM PST, Linus Torvalds <torvalds@linux-foundation.org> wrote: > >> >> >On Mon, Dec 26, 2022 at 11:52 AM Guenter Roeck <linux@roeck-us.net> wrote: > >> >> >> > >> >> >> fs/f2fs/inline.c: In function 'f2fs_move_inline_dirents': > >> >> >> include/linux/fortify-string.h:59:33: error: '__builtin_memset' pointer overflow between offset [28, 898293814] and size [-898293787, -1] [-Werror=array-bounds] > >> >> >> fs/f2fs/inline.c:430:9: note: in expansion of macro 'memset' > >> >> >> 430 | memset(dst.bitmap + src.nr_bitmap, 0, dst.nr_bitmap - src.nr_bitmap); > >> >> >> | ^~~~~~ > >> >> > > >> >> >Well, that's unfortunate. > >> >> > >> >> I'll look into this. > >> >> > >> > > >> >I did some more testing. The problem is seen with gcc 11.3.0, but not with > >> >gcc 12.2.0 nor with gcc 10.3.0. > >> > >> That's what I'd expect: 10 didn't have variable range tracking wired up to -Warray-bounds, 11 does, and we disable -Warray-bounds on 12 because of 3 separate 12-only GCC bugs. > >> > >> > gcc bug ? Should I switch to gcc 12.2.0 for > >> >powerpc when build testing the latest kernel ? > >> > >> Sure? But that'll just hide it. I suspect GCC has found a way for dst.nr_bitmap to be compile-time 27, so the size is always negative. > >> > >dst.nr_bitmap is initialized with SIZE_OF_DENTRY_BITMAP, > >which is defined as: > > > >#define NR_DENTRY_IN_BLOCK 214 /* the number of dentry in a block */ > >#define SIZE_OF_DIR_ENTRY 11 /* by byte */ > >#define SIZE_OF_DENTRY_BITMAP ((NR_DENTRY_IN_BLOCK + BITS_PER_BYTE - 1) / \ > > BITS_PER_BYTE) > > > >((214 + 8 - 1) / 8 = 27, so dst.nr_bitmap is indeed compile-time 27. > > > >Not sure how would know that src.nr_bitmap can be > 27, though. > >Am I missing something ? > > I think it's saying it can't rule out it being larger? I.e. there is no obvious bounds checking for it. Perhaps: > > if (src.nr_bitmap > dst.nr_bitmap) { > err = -EFSCORRUPTED; > goto out; > } >
After going through all calculations, using maximum values (or minimum values where appropriate) everywhere, I calculated that src.nr_bitmap is always <= 24. The actual inode is sanity checked in fs/f2fs/inode.c:sanity_check_inode().
Also, why is this only seen when I try to build powerpc test images ?
Thanks, Guenter
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