Messages in this thread | | | Date | Tue, 27 Dec 2022 19:40:30 -0800 | From | Kees Cook <> | Subject | Re: Linux 6.2-rc1 |
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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; }
-Kees
-- Kees Cook
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