From: Jaegeuk Kim <jaegeuk@kernel.org>
To: Chao Yu <yuchao0@huawei.com>
Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] Revert "f2fs: avoid out-of-range memory access"
Date: Mon, 5 Aug 2019 18:28:39 -0700 [thread overview]
Message-ID: <20190806012839.GD1029@jaegeuk-macbookpro.roam.corp.google.com> (raw)
In-Reply-To: <dd284020-77b0-1627-2fc2-bc51745adfd3@huawei.com>
On 08/06, Chao Yu wrote:
> On 2019/8/6 8:42, Jaegeuk Kim wrote:
> > On 08/02, Chao Yu wrote:
> >> As Pavel Machek reported:
> >>
> >> "We normally use -EUCLEAN to signal filesystem corruption. Plus, it is
> >> good idea to report it to the syslog and mark filesystem as "needing
> >> fsck" if filesystem can do that."
> >>
> >> Still we need improve the original patch with:
> >> - use unlikely keyword
> >> - add message print
> >> - return EUCLEAN
> >>
> >> However, after rethink this patch, I don't think we should add such
> >> condition check here as below reasons:
> >> - We have already checked the field in f2fs_sanity_check_ckpt(),
> >> - If there is fs corrupt or security vulnerability, there is nothing
> >> to guarantee the field is integrated after the check, unless we do
> >> the check before each of its use, however no filesystem does that.
> >> - We only have similar check for bitmap, which was added due to there
> >> is bitmap corruption happened on f2fs' runtime in product.
> >> - There are so many key fields in SB/CP/NAT did have such check
> >> after f2fs_sanity_check_{sb,cp,..}.
> >>
> >> So I propose to revert this unneeded check.
> >
> > IIRC, this came from security vulnerability report which can access
>
> I don't think that's correct report, since we have checked validation of that
> field during mount, if it can be ruined after that, any variables can't be trusted.
I assumed this was reproduced with a fuzzed image.
I'll check it with Ocean.
>
> Now we just check bitmaps at real-time, because we have encountered such bitmap
> corruption in product.
>
> Thanks,
>
> > out-of-boundary memory region. Could you write another patch to address the
> > above issues?
> >
> >>
> >> This reverts commit 56f3ce675103e3fb9e631cfb4131fc768bc23e9a.
> >>
> >> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> >> ---
> >> fs/f2fs/segment.c | 5 -----
> >> 1 file changed, 5 deletions(-)
> >>
> >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> >> index 9693fa4c8971..2eff9c008ae0 100644
> >> --- a/fs/f2fs/segment.c
> >> +++ b/fs/f2fs/segment.c
> >> @@ -3492,11 +3492,6 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi)
> >> seg_i = CURSEG_I(sbi, i);
> >> segno = le32_to_cpu(ckpt->cur_data_segno[i]);
> >> blk_off = le16_to_cpu(ckpt->cur_data_blkoff[i]);
> >> - if (blk_off > ENTRIES_IN_SUM) {
> >> - f2fs_bug_on(sbi, 1);
> >> - f2fs_put_page(page, 1);
> >> - return -EFAULT;
> >> - }
> >> seg_i->next_segno = segno;
> >> reset_curseg(sbi, i, 0);
> >> seg_i->alloc_type = ckpt->alloc_type[i];
> >> --
> >> 2.18.0.rc1
> > .
> >
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next prev parent reply other threads:[~2019-08-06 1:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 10:15 [f2fs-dev] [PATCH] Revert "f2fs: avoid out-of-range memory access" Chao Yu
2019-08-06 0:42 ` Jaegeuk Kim
2019-08-06 1:10 ` Chao Yu
2019-08-06 1:28 ` Jaegeuk Kim [this message]
2019-08-06 2:07 ` Chao Yu
2019-08-06 3:05 ` Jaegeuk Kim
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