From: Luis de Bethencourt Date: Wed, 30 Mar 2016 22:18:14 +0000 (+0100) Subject: btrfs: avoid overflowing f_bfree X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=41b34accb265e3a20211a7a8ef3625678f1c6ec7;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git btrfs: avoid overflowing f_bfree 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 Suggested-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index bdca79ce45f1..fe03efb5bec0 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);