Perform basic sanity checks of quota headers to avoid kernel crashes on
corrupted quota files.
CC: stable@xxxxxxxxxxxxxxx
Reported-by: syzbot+f816042a7ae2225f25ba@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
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
