On Nov 2, 2020, at 10:27 AM, Jan Kara jack@suse.cz wrote:

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 Signed-off-by: Jan Kara jack@suse.cz

Looks reasonable.

Reviewed-by: Andreas Dilger adilger@dilger.ca

---

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

diff --git a/fs/quota/quota_v2.c b/fs/quota/quota_v2.c index e69a2bfdd81c..c21106557a37 100644 --- a/fs/quota/quota_v2.c +++ b/fs/quota/quota_v2.c @@ -157,6 +157,25 @@ static int v2_read_file_info(struct super_block *sb, int type) 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); -- 2.16.4

Cheers, Andreas