[src/trunk]: src/sys/dev/scsipi Avoid buffer overflow when copying from bounc...

[mlelstv <mlelstv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/4f62f8acae77
branches:  trunk
changeset: 956324:4f62f8acae77
user:      mlelstv <mlelstv%NetBSD.org@localhost>
date:      Mon Oct 26 11:39:48 2020 +0000

description:
Avoid buffer overflow when copying from bounce buffer.
Fixes PR 54810

Don't use uninitialized pointer in split bounce buffer case and
free a partially allocated bounce buffer on error.

diffstat:

 sys/dev/scsipi/cd.c |  10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diffs (40 lines):

diff -r b84146f9e5be -r 4f62f8acae77 sys/dev/scsipi/cd.c
--- a/sys/dev/scsipi/cd.c       Mon Oct 26 07:37:52 2020 +0000
+++ b/sys/dev/scsipi/cd.c       Mon Oct 26 11:39:48 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cd.c,v 1.348 2020/09/29 03:04:03 msaitoh Exp $ */
+/*     $NetBSD: cd.c,v 1.349 2020/10/26 11:39:48 mlelstv Exp $ */
 
 /*-
  * Copyright (c) 1998, 2001, 2003, 2004, 2005, 2008 The NetBSD Foundation,
@@ -50,7 +50,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: cd.c,v 1.348 2020/09/29 03:04:03 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cd.c,v 1.349 2020/10/26 11:39:48 mlelstv Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -667,7 +667,7 @@
        cd_iosize(dksc->sc_dev, &count);
 
        bounce->head = skip * DEV_BSIZE;
-       bounce->lcount = count - bounce->head;
+       bounce->lcount = imin(count - bounce->head, bp->b_bcount);
        bounce->rcount = bp->b_bcount - bounce->lcount;
 
        error = cd_make_bounce_buffer(cd, bp, blkno, count, &lbp, bounce);
@@ -678,10 +678,10 @@
        count = total - count;
 
        if (count > 0) {
-               bounce->lbp->b_private = bounce;
                error = cd_make_bounce_buffer(cd, bp, blkno, count, &rbp, bounce);
                if (error) {
-                       putiobuf(bounce->lbp);
+                       free(lbp->b_data, M_DEVBUF);
+                       putiobuf(lbp);
                        goto bad;
                }
        } else