Messages in this thread Patch in this message | | | From | Luis de Bethencourt <> | Subject | [PATCH v2 2/2] btrfs: avoid overflowing f_bfree | Date | Wed, 30 Mar 2016 23:18:14 +0100 |
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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@osg.samsung.com> Suggested-by: David Sterba <dsterba@suse.com> --- Hi,
Thanks to Filipe Manana for spotting a mistake in the first version of this patch.
Luis
fs/btrfs/super.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index bdca79c..fe03efb 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2100,7 +2100,11 @@ 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
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