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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 17:42:15 -0700	[thread overview]
Message-ID: <20190806004215.GC98101@jaegeuk-macbookpro.roam.corp.google.com> (raw)
In-Reply-To: <20190802101548.96543-1-yuchao0@huawei.com>

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
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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  reply	other threads:[~2019-08-06  0:42 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 [this message]
2019-08-06  1:10   ` Chao Yu
2019-08-06  1:28     ` Jaegeuk Kim
2019-08-06  2:07       ` Chao Yu
2019-08-06  3:05         ` Jaegeuk Kim

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