[PATCH 087/145] ext4: fix overflows in SEEK_HOLE, SEEK_DATA implementations

[Kamal Mostafa]

3.8.13.5 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@xxxxxxx>

commit e7293fd146846e2a44d29e0477e0860c60fb856b upstream.

ext4_lblk_t is just u32 so multiplying it by blocksize can easily
overflow for files larger than 4 GB. Fix that by properly typing the
block offsets before shifting.

Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Reviewed-by: Zheng Liu <wenqing.lz@xxxxxxxxxx>
[ luis: backported to 3.8: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 fs/ext4/file.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 405565a..216a633 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -311,7 +311,7 @@ static int ext4_find_unwritten_pgoff(struct inode *inode,
 	blkbits = inode->i_sb->s_blocksize_bits;
 	startoff = *offset;
 	lastoff = startoff;
-	endoff = (map->m_lblk + map->m_len) << blkbits;
+	endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits;
 
 	index = startoff >> PAGE_CACHE_SHIFT;
 	end = endoff >> PAGE_CACHE_SHIFT;
@@ -456,7 +456,7 @@ static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 		ret = ext4_map_blocks(NULL, inode, &map, 0);
 		if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 			if (last != start)
-				dataoff = last << blkbits;
+				dataoff = (loff_t)last << blkbits;
 			break;
 		}
 
@@ -469,7 +469,7 @@ static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 		if (last >= es.start &&
 		    last < es.start + es.len) {
 			if (last != start)
-				dataoff = last << blkbits;
+				dataoff = (loff_t)last << blkbits;
 			break;
 		}
 
@@ -487,7 +487,7 @@ static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 		}
 
 		last++;
-		dataoff = last << blkbits;
+		dataoff = (loff_t)last << blkbits;
 	} while (last <= end);
 
 	mutex_unlock(&inode->i_mutex);
@@ -541,7 +541,7 @@ static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 		ret = ext4_map_blocks(NULL, inode, &map, 0);
 		if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 			last += ret;
-			holeoff = last << blkbits;
+			holeoff = (loff_t)last << blkbits;
 			continue;
 		}
 
@@ -554,7 +554,7 @@ static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 		if (last >= es.start &&
 		    last < es.start + es.len) {
 			last = es.start + es.len;
-			holeoff = last << blkbits;
+			holeoff = (loff_t)last << blkbits;
 			continue;
 		}
 
@@ -569,7 +569,7 @@ static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 							      &map, &holeoff);
 			if (!unwritten) {
 				last += ret;
-				holeoff = last << blkbits;
+				holeoff = (loff_t)last << blkbits;
 				continue;
 			}
 		}
-- 
1.8.1.2

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