Re: [PATCH v3] f2fs: avoid out-of-range memory access

From: Chao Yu
Date: Thu Jul 04 2019 - 03:22:22 EST


On 2019/7/3 23:33, Ocean Chen wrote:
> blk_off might over 512 due to fs corrupt and should
> be checked before being used.
> Use ENTRIES_IN_SUM to protect invalid memory access.
>
> --
> v2:
> - fix typo
> v3:
> - check blk_off before being used
> --
> Signed-off-by: Ocean Chen <oceanchen@xxxxxxxxxx>
> ---
> fs/f2fs/segment.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 8dee063c833f..c3eae3239345 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -3401,6 +3401,9 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi)
> if (seg_i->alloc_type == SSR)
> blk_off = sbi->blocks_per_seg;
>
> + if (blk_off >= ENTRIES_IN_SUM)
> + return -EFAULT;

- scripts/checkpatch.pl will complain such format.
- miss to call f2fs_put_page(page, 1) before return.

Thanks,

> +
> for (j = 0; j < blk_off; j++) {
> struct f2fs_summary *s;
> s = (struct f2fs_summary *)(kaddr + offset);
>