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Subject[PATCH 087/145] ext4: fix overflows in SEEK_HOLE, SEEK_DATA implementations
Date
3.8.13.5 -stable review patch.  If anyone has any objections, please let me know.

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

From: Jan Kara <jack@suse.cz>

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@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
[ luis: backported to 3.8: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
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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