Messages in this thread | | | Subject | Re: [PATCH] Revert "f2fs: avoid out-of-range memory access" | From | Chao Yu <> | Date | Tue, 6 Aug 2019 10:07:45 +0800 |
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On 2019/8/6 9:28, Jaegeuk Kim wrote: > 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 expect f2fs_sanity_check_ckpt() should reject mounting such 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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