From: Guenter Roeck <linux@roeck-us.net>
To: Kees Cook <kees@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
Peter Zijlstra <peterz@infradead.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Kees Cook <keescook@chromium.org>
Subject: Re: Linux 6.2-rc1
Date: Wed, 28 Dec 2022 06:44:08 -0800 [thread overview]
Message-ID: <20221228144408.GA873415@roeck-us.net> (raw)
In-Reply-To: <DE30CDA1-CFF4-49FE-B653-F4CA831EAA12@kernel.org>
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
next prev parent reply other threads:[~2022-12-28 14:44 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-25 22:07 Linux 6.2-rc1 Linus Torvalds
2022-12-26 19:52 ` Guenter Roeck
2022-12-26 20:56 ` Linus Torvalds
2022-12-26 21:03 ` Kees Cook
2022-12-26 22:10 ` Guenter Roeck
2022-12-27 0:29 ` Guenter Roeck
2022-12-27 1:32 ` Kees Cook
2022-12-27 5:52 ` Guenter Roeck
2022-12-28 3:40 ` Kees Cook
2022-12-28 14:44 ` Guenter Roeck [this message]
2023-01-07 0:06 ` Jaegeuk Kim
2022-12-26 22:41 ` Vlastimil Babka
2022-12-26 21:10 ` Max Filippov
2022-12-26 22:08 ` Guenter Roeck
2022-12-27 8:29 ` Build regressions/improvements in v6.2-rc1 Geert Uytterhoeven
2022-12-27 8:35 ` Geert Uytterhoeven
2023-01-01 1:33 ` Rob Landley
2023-01-01 12:24 ` Geert Uytterhoeven
2023-01-04 6:32 ` Michael Ellerman
2023-01-06 15:10 ` John Paul Adrian Glaubitz
2023-01-06 15:17 ` Geert Uytterhoeven
2023-01-06 15:18 ` Geert Uytterhoeven
2023-01-17 16:42 ` Calculating array sizes in C - was: " John Paul Adrian Glaubitz
2023-01-17 17:01 ` Geert Uytterhoeven
2023-01-17 17:06 ` John Paul Adrian Glaubitz
2023-01-17 20:05 ` Geert Uytterhoeven
2023-01-17 20:37 ` John Paul Adrian Glaubitz
2023-01-19 22:11 ` Michael.Karcher
2023-01-20 3:31 ` Rob Landley
2023-01-20 10:53 ` Segher Boessenkool
2023-01-20 18:29 ` Michael.Karcher
2023-01-20 8:49 ` John Paul Adrian Glaubitz
2023-01-20 19:29 ` Michael Karcher
2023-01-21 21:26 ` John Paul Adrian Glaubitz
2023-01-06 15:39 ` Alex Deucher
2023-01-04 19:01 ` Linux 6.2-rc1 Pali Rohár
2023-01-04 19:25 ` Linus Torvalds
2023-01-04 20:56 ` Pali Rohár
2023-01-04 21:27 ` Pali Rohár
2023-01-04 21:32 ` Linus Torvalds
2023-01-04 21:43 ` Jens Axboe
2023-01-05 11:25 ` Greg Kroah-Hartman
2023-01-05 15:26 ` Jens Axboe
2023-01-05 17:42 ` Pali Rohár
2023-01-05 17:45 ` Jens Axboe
2023-01-05 19:06 ` Linus Torvalds
2023-01-05 19:22 ` Pali Rohár
2023-01-05 19:40 ` Jens Axboe
2023-01-05 20:03 ` Linus Torvalds
2023-01-05 20:33 ` Jens Axboe
2023-01-06 16:58 ` Pali Rohár
2023-01-06 17:04 ` Jens Axboe
2023-01-28 19:34 ` pktcdvd Pali Rohár
2023-01-28 19:43 ` pktcdvd Linus Torvalds
2023-01-29 21:53 ` pktcdvd Jens Axboe
2023-01-29 21:55 ` pktcdvd Jens Axboe
2023-01-29 22:21 ` pktcdvd Pali Rohár
2023-01-29 22:34 ` pktcdvd Jens Axboe
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