[PATCH] f2fs: fix potential overflow

[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

[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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[PATCH] f2fs: fix potential overflow

[Chao Yu]

From: Chao Yu <yuchao0@huawei.com>

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>
---
 fs/f2fs/segment.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index a55647f61232..49fce2b56017 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -3692,14 +3692,17 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
 			} else {
 				memcpy(se->discard_map, se->cur_valid_map,
 							SIT_VBLOCK_MAP_SIZE);
-				sbi->discard_blks += old_valid_blocks -
-							se->valid_blocks;
+				sbi->discard_blks += old_valid_blocks;
+				sbi->discard_blks -= se->valid_blocks;
 			}
 		}
 
-		if (sbi->segs_per_sec > 1)
+		if (sbi->segs_per_sec > 1) {
 			get_sec_entry(sbi, start)->valid_blocks +=
-				se->valid_blocks - old_valid_blocks;
+							se->valid_blocks;
+			get_sec_entry(sbi, start)->valid_blocks -=
+							old_valid_blocks;
+		}
 	}
 	up_read(&curseg->journal_rwsem);
 
-- 
2.16.2.17.g38e79b1fd