From 1e60f8ff27bee2ff05d5f83bdd6a311a047fb7c1 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 12 Apr 2021 12:23:33 +0200 Subject: [PATCH] ext4: fix overflow in ext4_iomap_alloc() commit d0b040f5f2557b2f507c01e88ad8cff424fdc6a9 upstream. A code in iomap alloc may overflow block number when converting it to byte offset. Luckily this is mostly harmless as we will just use more expensive method of writing using unwritten extents even though we are writing beyond i_size. Cc: stable@kernel.org Fixes: 378f32bab371 ("ext4: introduce direct I/O write using iomap infrastructure") Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20210412102333.2676-4-jack@suse.cz Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index fe6045a46599..211acfba3af7 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3418,7 +3418,7 @@ static int ext4_iomap_alloc(struct inode *inode, struct ext4_map_blocks *map, * i_disksize out to i_size. This could be beyond where direct I/O is * happening and thus expose allocated blocks to direct I/O reads. */ - else if ((map->m_lblk * (1 << blkbits)) >= i_size_read(inode)) + else if (((loff_t)map->m_lblk << blkbits) >= i_size_read(inode)) m_flags = EXT4_GET_BLOCKS_CREATE; else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) m_flags = EXT4_GET_BLOCKS_IO_CREATE_EXT;