From 306df0716aa285d378cc948fafed53c6ed895fe6 Mon Sep 17 00:00:00 2001 From: Dave Young Date: Wed, 8 Feb 2012 22:07:19 +0100 Subject: [PATCH] loop: zero fill bio instead of return -EIO for partial read commit 8268f5a741 ("deny partial write for loop dev fd") tried to fix the loop device partial read information leak problem. But it changed the semantics of read behavior. When we read beyond the end of the device we should get 0 bytes, which is normal behavior, we should not just return -EIO Instead of returning -EIO, zero out the bio to avoid information leak in case of partail read. Signed-off-by: Dave Young Reviewed-by: Jeff Moyer Tested-by: Jeff Moyer Cc: Dmitry Monakhov Signed-off-by: Andrew Morton Signed-off-by: Jens Axboe --- drivers/block/loop.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index f00257782fcc..cd504353b278 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -356,14 +356,14 @@ lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd) return __splice_from_pipe(pipe, sd, lo_splice_actor); } -static int +static ssize_t do_lo_receive(struct loop_device *lo, struct bio_vec *bvec, int bsize, loff_t pos) { struct lo_read_data cookie; struct splice_desc sd; struct file *file; - long retval; + ssize_t retval; cookie.lo = lo; cookie.page = bvec->bv_page; @@ -379,26 +379,28 @@ do_lo_receive(struct loop_device *lo, file = lo->lo_backing_file; retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor); - if (retval < 0) - return retval; - if (retval != bvec->bv_len) - return -EIO; - return 0; + return retval; } static int lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos) { struct bio_vec *bvec; - int i, ret = 0; + ssize_t s; + int i; bio_for_each_segment(bvec, bio, i) { - ret = do_lo_receive(lo, bvec, bsize, pos); - if (ret < 0) + s = do_lo_receive(lo, bvec, bsize, pos); + if (s < 0) + return s; + + if (s != bvec->bv_len) { + zero_fill_bio(bio); break; + } pos += bvec->bv_len; } - return ret; + return 0; } static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)