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SubjectRe: [f2fs-dev] [PATCH] f2fs: check memory boundary by insane namelen
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Hi, Jaegeuk and Chao,

On 2018/11/15 15:50, Jaegeuk Kim wrote:
> If namelen is corrupted to have very long value, fill_dentries can copy
> wrong memory area.
>
Is there any scenario that could hit this corruption? Or this is triggered
by fuzzing injection?

thanks,
Sheng Yong

> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
> fs/f2fs/dir.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index bacc667950b6..c0c845da12fa 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -808,6 +808,17 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
> de_name.name = d->filename[bit_pos];
> de_name.len = le16_to_cpu(de->name_len);
>
> + /* check memory boundary before moving forward */
> + bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
> + if (unlikely(bit_pos > d->max)) {
> + f2fs_msg(sbi->sb, KERN_WARNING,
> + "%s: corrupted namelen=%d, run fsck to fix.",
> + __func__, le16_to_cpu(de->name_len));
> + set_sbi_flag(sbi, SBI_NEED_FSCK);
> + err = -EINVAL;
> + goto out;
> + }
> +
> if (f2fs_encrypted_inode(d->inode)) {
> int save_len = fstr->len;
>
> @@ -830,7 +841,6 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
> if (readdir_ra)
> f2fs_ra_node_page(sbi, le32_to_cpu(de->ino));
>
> - bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
> ctx->pos = start_pos + bit_pos;
> }
> out:
>

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