linux-kernel - [PATCH 5/6] dax: use copy_to_iter_mcsafe() in dax_iomap

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: <152520753501.36522.5856044229551545705.stgit@dwillia2-desk3.amr.corp.intel.com>
Date:   Tue, 01 May 2018 13:45:35 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-nvdimm@...ts.01.org
Cc:     x86@...nel.org, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Tony Luck <tony.luck@...el.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...capital.net>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, tony.luck@...el.com
Subject: [PATCH 5/6] dax: use copy_to_iter_mcsafe() in dax_iomap_actor()

Protect the dax read(2) path from media errors with
copy_to_iter_mcsafe(). If a machine check truncates a transfer we abort
the remainder of the transfer and communicate the number of bytes
successfully completed.

Cc: <x86@...nel.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Tony Luck <tony.luck@...el.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 fs/dax.c |   20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index aaec72ded1b6..e7894ab791cb 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -991,6 +991,7 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 	struct iov_iter *iter = data;
 	loff_t end = pos + length, done = 0;
 	ssize_t ret = 0;
+	size_t xfer;
 	int id;
 
 	if (iov_iter_rw(iter) == READ) {
@@ -1054,18 +1055,19 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		 * vfs_write(), depending on which operation we are doing.
 		 */
 		if (iov_iter_rw(iter) == WRITE)
-			map_len = dax_copy_from_iter(dax_dev, pgoff, kaddr,
+			xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr,
 					map_len, iter);
 		else
-			map_len = copy_to_iter(kaddr, map_len, iter);
-		if (map_len <= 0) {
-			ret = map_len ? map_len : -EFAULT;
-			break;
-		}
+			xfer = copy_to_iter_mcsafe(kaddr, map_len, iter);
 
-		pos += map_len;
-		length -= map_len;
-		done += map_len;
+		pos += xfer;
+		length -= xfer;
+		done += xfer;
+
+		if (xfer == 0)
+			ret = -EFAULT;
+		if (xfer < map_len)
+			break;
 	}
 	dax_read_unlock(id);