[f2fs-dev] [PATCH] f2fs: fix potential overflow

[f2fs-dev] [PATCH] f2fs: fix potential overflow

[Chao Yu]

We expect 64-bit calculation result from below statement, however
in 32-bit machine, looped left shift operation on pgoff_t type
variable may cause overflow issue, fix it by forcing type cast.

page->index << PAGE_SHIFT;

Fixes: 26de9b117130 ("f2fs: avoid unnecessary updating inode during fsync")
Fixes: 0a2aa8fbb969 ("f2fs: refactor __exchange_data_block for speed up")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
 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 58f4bade6c2b..8f70dfcafab3 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2204,7 +2204,7 @@ 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 nr_pages = DIV_ROUND_UP(i_size, PAGE_SIZE);
 	unsigned offset = 0;
 	bool need_balance_fs = false;
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index a7d855efc294..3564cb6a4c18 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1139,7 +1139,7 @@ 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));
-- 
2.18.0.rc1



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