[PATCH 4.9 20/32] quota: Dont overflow quota file offsets

Greg Kroah-Hartman
2021-01-07T14:20:00Z

From: Jan Kara <jack@suse.cz>

[ Upstream commit 10f04d40a9fa29785206c619f80d8beedb778837 ]

The on-disk quota format supports quota files with upto 2^32 blocks. Be
careful when computing quota file offsets in the quota files from block
numbers as they can overflow 32-bit types. Since quota files larger than
4GB would require ~26 millions of quota users, this is mostly a
theoretical concern now but better be careful, fuzzers would find the
problem sooner or later anyway...

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/quota/quota_tree.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c
index 0738972e8d3f0..ecd9887b0d1fe 100644
--- a/fs/quota/quota_tree.c
+++ b/fs/quota/quota_tree.c
@@ -61,7 +61,7 @@ static ssize_t read_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)

memset(buf, 0, info->dqi_usable_bs);
return sb->s_op->quota_read(sb, info->dqi_type, buf,
- info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
+ info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
}

static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
@@ -70,7 +70,7 @@ static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
ssize_t ret;

ret = sb->s_op->quota_write(sb, info->dqi_type, buf,
- info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
+ info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
if (ret != info->dqi_usable_bs) {
quota_error(sb, "dquota write failed");
if (ret >= 0)
@@ -283,7 +283,7 @@ static uint find_free_dqentry(struct qtree_mem_dqinfo *info,
blk);
goto out_buf;
}
- dquot->dq_off = (blk << info->dqi_blocksize_bits) +
+ dquot->dq_off = ((loff_t)blk << info->dqi_blocksize_bits) +
sizeof(struct qt_disk_dqdbheader) +
i * info->dqi_entry_size;
kfree(buf);
@@ -558,7 +558,7 @@ static loff_t find_block_dqentry(struct qtree_mem_dqinfo *info,
ret = -EIO;
goto out_buf;
} else {
- ret = (blk << info->dqi_blocksize_bits) + sizeof(struct
+ ret = ((loff_t)blk << info->dqi_blocksize_bits) + sizeof(struct
qt_disk_dqdbheader) + i * info->dqi_entry_size;
}
out_buf:
--
2.27.0