ext4: 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>
Signed-off-by: Amit Arora <aarora@in.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ee611daf0748..8a8f9f0be911 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3708,6 +3708,11 @@ 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;