--- /dev/null
+From b86e33075ed1909d8002745b56ecf73b833db143 Mon Sep 17 00:00:00 2001
+From: Wei Fang <fangwei1@huawei.com>
+Date: Sun, 22 Jan 2017 12:21:02 +0800
+Subject: f2fs: fix a dead loop in f2fs_fiemap()
+
+From: Wei Fang <fangwei1@huawei.com>
+
+commit b86e33075ed1909d8002745b56ecf73b833db143 upstream.
+
+A dead loop can be triggered in f2fs_fiemap() using the test case
+as below:
+
+ ...
+ fd = open();
+ fallocate(fd, 0, 0, 4294967296);
+ ioctl(fd, FS_IOC_FIEMAP, fiemap_buf);
+ ...
+
+It's caused by an overflow in __get_data_block():
+ ...
+ bh->b_size = map.m_len << inode->i_blkbits;
+ ...
+map.m_len is an unsigned int, and bh->b_size is a size_t which is 64 bits
+on 64 bits archtecture, type conversion from an unsigned int to a size_t
+will result in an overflow.
+
+In the above-mentioned case, bh->b_size will be zero, and f2fs_fiemap()
+will call get_data_block() at block 0 again an again.
+
+Fix this by adding a force conversion before left shift.
+
+Signed-off-by: Wei Fang <fangwei1@huawei.com>
+Acked-by: Chao Yu <yuchao0@huawei.com>
+Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
+Cc: Guenter Roeck <linux@roeck-us.net>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ fs/f2fs/data.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/fs/f2fs/data.c
++++ b/fs/f2fs/data.c
+@@ -844,7 +844,7 @@ static int __get_data_block(struct inode
+ if (!ret) {
+ map_bh(bh, inode->i_sb, map.m_pblk);
+ bh->b_state = (bh->b_state & ~F2FS_MAP_FLAGS) | map.m_flags;
+- bh->b_size = map.m_len << inode->i_blkbits;
++ bh->b_size = (u64)map.m_len << inode->i_blkbits;
+ }
+ return ret;
+ }