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SubjectRe: [PATCH 4.19 026/239] f2fs: fix to do sanity check in is_alive()
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On 2022/1/25 4:36, Pavel Machek wrote:
> Hi!
>
>> From: Chao Yu <chao@kernel.org>
>>
>> commit 77900c45ee5cd5da63bd4d818a41dbdf367e81cd upstream.
>>
>> In fuzzed image, SSA table may indicate that a data block belongs to
>> invalid node, which node ID is out-of-range (0, 1, 2 or max_nid), in
>> order to avoid migrating inconsistent data in such corrupted image,
>> let's do sanity check anyway before data block migration.
>
> This may be good idea, but AFAICT this leads to leak of page reference.

Hi Pavel,

Oops, you're right, my bad.

>
>> +++ b/fs/f2fs/gc.c
>> @@ -589,6 +589,9 @@ static bool is_alive(struct f2fs_sb_info
>> set_sbi_flag(sbi, SBI_NEED_FSCK);
>> }
>>
>> + if (f2fs_check_nid_range(sbi, dni->ino))
>> + return false;
>> +
>> *nofs = ofs_of_node(node_page);
>> source_blkaddr = datablock_addr(NULL, node_page, ofs_in_node);
>> f2fs_put_page(node_page, 1);
>
> AFAICT f2fs_put_page() needs to be done in the error path, too.
>
> (Problem seems to exist in mainline, too).
>
> Something like this?

Could you please send a formal patch to f2fs mailing list for better review?

Anyway, thanks a lot for the report and the patch!

Thanks,

>
> Signed-off-by: Pavel Machek <pavel@denx.de>
>
> Best regards,
> Pavel
>
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index ee308a8de432..e020804f7b07 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -1038,8 +1038,10 @@ static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> set_sbi_flag(sbi, SBI_NEED_FSCK);
> }
>
> - if (f2fs_check_nid_range(sbi, dni->ino))
> + if (f2fs_check_nid_range(sbi, dni->ino)) {
> + f2fs_put_page(node_page, 1);
> return false;
> + }
>
> *nofs = ofs_of_node(node_page);
> source_blkaddr = data_blkaddr(NULL, node_page, ofs_in_node);
>
>

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