[PATCH 2/2] btrfs: avoid overflowing f_bfree
From: Luis de Bethencourt <hidden>
Date: 2016-03-30 20:53:53
Also in:
lkml
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
Since mixed block groups accounting isn't byte-accurate and f_bree is an unsigned integer, it could overflow. Avoid this. Signed-off-by: Luis de Bethencourt <redacted> Suggested-by: David Sterba <dsterba@suse.com> --- fs/btrfs/super.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index bdca79c..93376d0 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c@@ -2101,6 +2101,11 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf) /* Account global block reserve as used, it's in logical size already */ spin_lock(&block_rsv->lock); buf->f_bfree -= block_rsv->size >> bits; + /* Mixed block groups accounting is not byte-accurate, avoid overflow */ + if (buf->f_bfree >= block_rsv->size >> bits) + buf->f_bfree -= block_rsv->size >> bits; + else + buf->f_bfree = 0; spin_unlock(&block_rsv->lock); buf->f_bavail = div_u64(total_free_data, factor);
--
2.5.3