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Date: Sun, 5 Jun 2016 15:24:27 -0700
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Luis de Bethencourt <luisbg@....samsung.com>,
David Sterba <dsterba@...e.com>
Subject: [PATCH 4.5 112/128] btrfs: avoid overflowing f_bfree
4.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Luis de Bethencourt <luisbg@....samsung.com>
commit 41b34accb265e3a20211a7a8ef3625678f1c6ec7 upstream.
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 <luisbg@....samsung.com>
Suggested-by: David Sterba <dsterba@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
fs/btrfs/super.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2073,7 +2073,11 @@ static int btrfs_statfs(struct dentry *d
/* 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);
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