From: Jan Kara Date: Fri, 22 Nov 2019 00:14:38 +0000 (-0800) Subject: iomap: Fix pipe page leakage during splicing X-Git-Tag: v5.5-rc1~122^2 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=419e9c38aa075ed0cd3c13d47e15954b686bcdb6;p=linux.git iomap: Fix pipe page leakage during splicing When splicing using iomap_dio_rw() to a pipe, we may leak pipe pages because bio_iov_iter_get_pages() records that the pipe will have full extent worth of data however if file size is not block size aligned iomap_dio_rw() returns less than what bio_iov_iter_get_pages() set up and splice code gets confused leaking a pipe page with the file tail. Handle the situation similarly to the old direct IO implementation and revert iter to actually returned read amount which makes iter consistent with value returned from iomap_dio_rw() and thus the splice code is happy. Fixes: ff6a9292e6f6 ("iomap: implement direct I/O") CC: stable@vger.kernel.org Reported-by: syzbot+991400e8eba7e00a26e1@syzkaller.appspotmail.com Signed-off-by: Jan Kara Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig --- diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index b77ec2acb066..420c0c82f0ac 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -502,8 +502,15 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, } pos += ret; - if (iov_iter_rw(iter) == READ && pos >= dio->i_size) + if (iov_iter_rw(iter) == READ && pos >= dio->i_size) { + /* + * We only report that we've read data up to i_size. + * Revert iter to a state corresponding to that as + * some callers (such as splice code) rely on it. + */ + iov_iter_revert(iter, pos - dio->i_size); break; + } } while ((count = iov_iter_count(iter)) > 0); blk_finish_plug(&plug);