Re: [PATCH 4.19 034/118] f2fs: fix to avoid panic in f2fs_inplace_write_data()

From: Pavel Machek
Date: Sun Jun 16 2019 - 15:59:54 EST


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?

Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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