From: Chao Yu <yuchao0@huawei.com>
To: <jaegeuk@kernel.org>
Cc: <linux-f2fs-devel@lists.sourceforge.net>,
<linux-kernel@vger.kernel.org>, <chao@kernel.org>,
<drosen@google.com>, Chao Yu <yuchao0@huawei.com>
Subject: [PATCH 1/2] f2fs: fix to avoid potential negative .f_bfree
Date: Fri, 26 Apr 2019 17:57:53 +0800 [thread overview]
Message-ID: <20190426095754.85784-1-yuchao0@huawei.com> (raw)
When calculating .f_bfree value in f2fs_statfs(), sbi->unusable_block_count
can be increased after the judgment condition, result in overflow of
.f_bfree in later calculation. This patch fixes to use a temporary signed
variable to save the calculation result of .f_bfree.
if (unlikely(buf->f_bfree <= sbi->unusable_block_count))
buf->f_bfree = 0;
else
buf->f_bfree -= sbi->unusable_block_count;
Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
fs/f2fs/super.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 2376bb01b5c4..fcc9793dbc2c 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1216,6 +1216,7 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
block_t total_count, user_block_count, start_count;
u64 avail_node_count;
+ long long bfree;
total_count = le64_to_cpu(sbi->raw_super->block_count);
user_block_count = sbi->user_block_count;
@@ -1226,10 +1227,12 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
buf->f_blocks = total_count - start_count;
buf->f_bfree = user_block_count - valid_user_blocks(sbi) -
sbi->current_reserved_blocks;
- if (unlikely(buf->f_bfree <= sbi->unusable_block_count))
+
+ bfree = buf->f_bfree - sbi->unusable_block_count;
+ if (unlikely(bfree < 0))
buf->f_bfree = 0;
else
- buf->f_bfree -= sbi->unusable_block_count;
+ buf->f_bfree = bfree;
if (buf->f_bfree > F2FS_OPTION(sbi).root_reserved_blocks)
buf->f_bavail = buf->f_bfree -
--
2.18.0.rc1
next reply other threads:[~2019-04-26 9:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-26 9:57 Chao Yu [this message]
2019-04-26 9:57 ` [PATCH 2/2] f2fs: fix to handle error in f2fs_disable_checkpoint() Chao Yu
2019-04-28 13:47 ` [PATCH 1/2] f2fs: fix to avoid potential negative .f_bfree Jaegeuk Kim
2019-04-29 14:13 ` Chao Yu
2019-04-30 2:54 ` Jaegeuk Kim
2019-04-30 3:14 ` Chao Yu
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