On Tue, Jun 07, 2022 at 12:24:38AM -0400, Theodore Ts'o wrote:
> E2fsck replays the journal before sanity checking the full superblock.
> So it's possible that the journal inode number is not valid relative
> to the number of block groups. So to avoid potentially an array
> bounds overrun, sanity check this before trying to find the journal
> inode.
Looks good.
Reviewed-by: Lukas Czerner <lczerner@xxxxxxxxxx>
>
> Reported-by: Nils Bars <nils.bars@xxxxxx>
> Reported-by: Moritz Schlögel <moritz.schloegel@xxxxxx>
> Reported-by: Nico Schiller <nico.schiller@xxxxxx>
> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
> ---
> e2fsck/journal.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/e2fsck/journal.c b/e2fsck/journal.c
> index 2e867234..12487e3d 100644
> --- a/e2fsck/journal.c
> +++ b/e2fsck/journal.c
> @@ -989,7 +989,14 @@ static errcode_t e2fsck_get_journal(e2fsck_t ctx, journal_t **ret_journal)
> journal->j_blocksize = ctx->fs->blocksize;
>
> if (uuid_is_null(sb->s_journal_uuid)) {
> - if (!sb->s_journal_inum) {
> + /*
> + * The full set of superblock sanity checks haven't
> + * been performed yet, so we need to do some basic
> + * checks here to avoid potential array overruns.
> + */
> + if (!sb->s_journal_inum ||
> + (sb->s_journal_inum >
> + (ctx->fs->group_desc_count * sb->s_inodes_per_group))) {
> retval = EXT2_ET_BAD_INODE_NUM;
> goto errout;
> }
> --
> 2.31.0
>
