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    Subject[PATCH 5.4 069/453] quota: Sanity-check quota file headers on load
    Date
    From: Jan Kara <jack@suse.cz>

    commit 11c514a99bb960941535134f0587102855e8ddee upstream.

    Perform basic sanity checks of quota headers to avoid kernel crashes on
    corrupted quota files.

    CC: stable@vger.kernel.org
    Reported-by: syzbot+f816042a7ae2225f25ba@syzkaller.appspotmail.com
    Reviewed-by: Andreas Dilger <adilger@dilger.ca>
    Signed-off-by: Jan Kara <jack@suse.cz>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/quota/quota_v2.c | 19 +++++++++++++++++++
    1 file changed, 19 insertions(+)

    --- a/fs/quota/quota_v2.c
    +++ b/fs/quota/quota_v2.c
    @@ -159,6 +159,25 @@ static int v2_read_file_info(struct supe
    qinfo->dqi_entry_size = sizeof(struct v2r1_disk_dqblk);
    qinfo->dqi_ops = &v2r1_qtree_ops;
    }
    + ret = -EUCLEAN;
    + /* Some sanity checks of the read headers... */
    + if ((loff_t)qinfo->dqi_blocks << qinfo->dqi_blocksize_bits >
    + i_size_read(sb_dqopt(sb)->files[type])) {
    + quota_error(sb, "Number of blocks too big for quota file size (%llu > %llu).",
    + (loff_t)qinfo->dqi_blocks << qinfo->dqi_blocksize_bits,
    + i_size_read(sb_dqopt(sb)->files[type]));
    + goto out;
    + }
    + if (qinfo->dqi_free_blk >= qinfo->dqi_blocks) {
    + quota_error(sb, "Free block number too big (%u >= %u).",
    + qinfo->dqi_free_blk, qinfo->dqi_blocks);
    + goto out;
    + }
    + if (qinfo->dqi_free_entry >= qinfo->dqi_blocks) {
    + quota_error(sb, "Block with free entry too big (%u >= %u).",
    + qinfo->dqi_free_entry, qinfo->dqi_blocks);
    + goto out;
    + }
    ret = 0;
    out:
    up_read(&dqopt->dqio_sem);

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