linux-kernel - [PATCH v1 50/54] fs/buffer.c: use bvec iterator to truncate the bio

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1482854706-14128-19-git-send-email-tom.leiming@gmail.com>
Date:   Wed, 28 Dec 2016 00:04:59 +0800
From:   Ming Lei <tom.leiming@...il.com>
To:     Jens Axboe <axboe@...com>, linux-kernel@...r.kernel.org
Cc:     linux-block@...r.kernel.org, Christoph Hellwig <hch@...radead.org>,
        Ming Lei <tom.leiming@...il.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org (open list:FILESYSTEMS (VFS and
        infrastructure))
Subject: [PATCH v1 50/54] fs/buffer.c: use bvec iterator to truncate the bio

For making multipage bvec working well.

Signed-off-by: Ming Lei <tom.leiming@...il.com>
---
 fs/buffer.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 63d2f40c21fd..014892593f57 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3063,8 +3063,7 @@ void guard_bio_eod(int op, struct bio *bio)
 	unsigned truncated_bytes;
 	/*
 	 * It is safe to truncate the last bvec in the following way
-	 * even though multipage bvec is supported, but we need to
-	 * fix the parameters passed to zero_user().
+	 * even though multipage bvec is supported.
 	 */
 	struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
 
@@ -3087,15 +3086,21 @@ void guard_bio_eod(int op, struct bio *bio)
 	/* Uhhuh. We've got a bio that straddles the device size! */
 	truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9);
 
-	/* Truncate the bio.. */
-	bio->bi_iter.bi_size -= truncated_bytes;
-	bvec->bv_len -= truncated_bytes;
-
 	/* ..and clear the end of the buffer for reads */
 	if (op == REQ_OP_READ) {
-		zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len,
-				truncated_bytes);
+		struct bvec_iter start = BVEC_ITER_ALL_INIT;
+		struct bvec_iter iter;
+		struct bio_vec bv;
+
+		start.bi_bvec_done = bvec->bv_len - truncated_bytes;
+
+		__bvec_for_each_sp_bvec(bv, bvec, iter, start)
+			zero_user(bv.bv_page, bv.bv_offset, bv.bv_len);
 	}
+
+	/* Truncate the bio.. */
+	bio->bi_iter.bi_size -= truncated_bytes;
+	bvec->bv_len -= truncated_bytes;
 }
 
 static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
-- 
2.7.4