Re: [PATCH] lib/ext2fs: Validity checks for ext2fs_inode_scan_goto_blockgroup()

Darrick J. Wong
2023-12-01T16:24:11Z

On Thu, Nov 30, 2023 at 04:01:18PM -0800, Brian Norris wrote:
> We don't validate the 'group' argument, so it's easy to get underflows
> or crashes here.
>
> This resolves issues seen in ureadahead, when it uses an old packfile
> (with mismatching group indices) with a new filesystem.

Say what now? The boot time pre-caching thing Ubuntu used to have?
https://manpages.ubuntu.com/manpages/trusty/man8/ureadahead.8.html

--D

> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
>
> lib/ext2fs/inode.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c
> index 957d5aa9f9d6..96d854b5fb69 100644
> --- a/lib/ext2fs/inode.c
> +++ b/lib/ext2fs/inode.c
> @@ -313,6 +313,9 @@ static errcode_t get_next_blockgroup(ext2_inode_scan scan)
> errcode_t ext2fs_inode_scan_goto_blockgroup(ext2_inode_scan scan,
> int group)
> {
> + if (group <= 0 || group >= scan->fs->group_desc_count)
> + return EXT2_ET_INVALID_ARGUMENT;
> +
> scan->current_group = group - 1;
> scan->groups_left = scan->fs->group_desc_count - group;
> scan->bad_block_ptr = 0;
> --
> 2.43.0.rc2.451.g8631bc7472-goog
>
>