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SubjectRe: [PATCH 4.19 034/118] f2fs: fix to avoid panic in f2fs_inplace_write_data()
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Hi Pavel,

On 2019/6/17 3:54, Pavel Machek wrote:
> Hi!
>
>> [ Upstream commit 05573d6ccf702df549a7bdeabef31e4753df1a90 ]
>>
>> As Jungyeon reported in bugzilla:
>>
>> https://bugzilla.kernel.org/show_bug.cgi?id=203239
>>
>> - Overview
>> When mounting the attached crafted image and running program, following errors are reported.
>> Additionally, it hangs on sync after running program.
>>
>> The image is intentionally fuzzed from a normal f2fs image for testing.
>> Compile options for F2FS are as follows.
>> CONFIG_F2FS_FS=y
> ...
>> The reason is f2fs_inplace_write_data() will trigger kernel panic due
>> to data block locates in node type segment.
>>
>> To avoid panic, let's just return error code and set SBI_NEED_FSCK to
>> give a hint to fsck for latter repairing.
>
>> index 03fa2c4d3d79..8fc3edb6760c 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -3069,13 +3069,18 @@ int f2fs_inplace_write_data(struct f2fs_io_info *fio)
>> {
>> int err;
>> struct f2fs_sb_info *sbi = fio->sbi;
>> + unsigned int segno;
>>
>> fio->new_blkaddr = fio->old_blkaddr;
>> /* i/o temperature is needed for passing down write hints */
>> __get_segment_type(fio);
>>
>> - f2fs_bug_on(sbi, !IS_DATASEG(get_seg_entry(sbi,
>> - GET_SEGNO(sbi, fio->new_blkaddr))->type));
>> + segno = GET_SEGNO(sbi, fio->new_blkaddr);
>> +
>> + if (!IS_DATASEG(get_seg_entry(sbi, segno)->type)) {
>> + set_sbi_flag(sbi, SBI_NEED_FSCK);
>> + return -EFAULT;
>> + }
>>
>
> Would it make sense to print some kind of debug message, as we do in
> the other error cases?

Although it's corner case, I think it will be better to do that, let me add it
in another patch.

Thanks for reminding. :)

Thanks,

>
> Best regards,
> Pavel
>

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