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Date: Mon, 12 Apr 2021 12:30:45 +0100 From: Matthew Wilcox <willy@...radead.org> To: Jan Kara <jack@...e.cz> Cc: Ted Tso <tytso@....edu>, linux-ext4@...r.kernel.org, Eric Whitney <enwlinux@...il.com>, linux-fsdevel@...r.kernel.org, "Darrick J . Wong" <djwong@...nel.org> Subject: Re: [PATCH 3/3] ext4: Fix overflow in ext4_iomap_alloc() On Mon, Apr 12, 2021 at 12:23:33PM +0200, Jan Kara wrote: > A code in iomap alloc may overblock block number when converting it to "overflow"? > 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. > > Fixes: 378f32bab371 ("ext4: introduce direct I/O write using iomap infrastructure") > Signed-off-by: Jan Kara <jack@...e.cz> > --- > 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 0948a43f1b3d..7cebbb2d2e34 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3420,7 +3420,7 @@ 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; > -- > 2.26.2 >
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