From b86e33075ed1909d8002745b56ecf73b833db143 Mon Sep 17 00:00:00 2001 From: Wei Fang Date: Sun, 22 Jan 2017 12:21:02 +0800 Subject: [PATCH] f2fs: fix a dead loop in f2fs_fiemap() 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 Acked-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/data.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 2ea8021..3b5f1d1 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -964,7 +964,7 @@ static int __get_data_block(struct inode *inode, sector_t iblock, if (!err) { 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 err; } -- 2.7.4