[PATCH AUTOSEL 4.14 348/371] f2fs: fix potential overflow

Sasha Levin
2020-01-16T17:32:50Z

From: Chao Yu <yuchao0@huawei.com>

[ Upstream commit a9af3fdcc4258af406879eca63d82e9d6baa892e ]

In build_sit_entries(), if valid_blocks in SIT block is smaller than
valid_blocks in journal, for below calculation:

sbi->discard_blks += old_valid_blocks - se->valid_blocks;

There will be two times potential overflow:
- old_valid_blocks - se->valid_blocks will overflow, and be a very
large number.
- sbi->discard_blks += result will overflow again, comes out a correct
result accidently.

Anyway, it should be fixed.

Fixes: d600af236da5 ("f2fs: avoid unneeded loop in build_sit_entries")
Fixes: 1f43e2ad7bff ("f2fs: introduce CP_TRIMMED_FLAG to avoid unneeded discard")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/f2fs/data.c | 2 +-
fs/f2fs/file.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index ac3fa4bbed2d..afe7dcfff036 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1512,7 +1512,7 @@ static int __write_data_page(struct page *page, bool *submitted,
loff_t i_size = i_size_read(inode);
const pgoff_t end_index = ((unsigned long long) i_size)
>> PAGE_SHIFT;
- loff_t psize = (page->index + 1) << PAGE_SHIFT;
+ loff_t psize = (loff_t)(page->index + 1) << PAGE_SHIFT;
unsigned offset = 0;
bool need_balance_fs = false;
int err = 0;
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index a90173b856f6..d98acc20a38a 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1059,7 +1059,7 @@ static int __clone_blkaddrs(struct inode *src_inode, struct inode *dst_inode,
}
dn.ofs_in_node++;
i++;
- new_size = (dst + i) << PAGE_SHIFT;
+ new_size = (loff_t)(dst + i) << PAGE_SHIFT;
if (dst_inode->i_size < new_size)
f2fs_i_size_write(dst_inode, new_size);
} while (--ilen && (do_replace[i] || blkaddr[i] == NULL_ADDR));
--
2.20.1