[PATCH] ext4: Prevent creation of files larger than RLIMIT_FSIZE using fallocate

[Nikanth Karthikesan <knikanth@suse.de>]

I assumed that Amit would send a patch with s-o-b, if not, please take
this patch.

Thanks
Nikanth

Prevent creation of files larger than RLIMIT_FSIZE using fallocate.

Currently using posix_fallocate one can bypass an RLIMIT_FSIZE limit
and create a file larger than the limit. Add a check for that.


Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>

---

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 236b834..39b8123 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3672,6 +3672,11 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
 	 */
 	credits = ext4_chunk_trans_blocks(inode, max_blocks);
 	mutex_lock(&inode->i_mutex);
+	ret = inode_newsize_ok(inode, (len + offset));
+	if (ret) {
+		mutex_unlock(&inode->i_mutex);
+		return ret;
+	}
 retry:
 	while (ret >= 0 && ret < max_blocks) {
 		block = block + ret;