[src/trunk]: src/sys/fs/udf Fix serious issue with recordable media formatted...

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

details:   https://anonhg.NetBSD.org/src/rev/cbb51ab601b1
branches:  trunk
changeset: 1027708:cbb51ab601b1
user:      reinoud <reinoud%NetBSD.org@localhost>
date:      Thu Dec 16 22:19:08 2021 +0000

description:
Fix serious issue with recordable media formatted with Win10. When closing it
after modification the VAT was written out corrupted making the disc
unreadable anymore on remount. Thanks for ig@ for spotting it in the wild!

diffstat:

 sys/fs/udf/udf_subr.c |  43 ++++++++++++++++++++++++++++++++-----------
 1 files changed, 32 insertions(+), 11 deletions(-)

diffs (89 lines):

diff -r 8e0971c71a2e -r cbb51ab601b1 sys/fs/udf/udf_subr.c
--- a/sys/fs/udf/udf_subr.c     Thu Dec 16 21:39:53 2021 +0000
+++ b/sys/fs/udf/udf_subr.c     Thu Dec 16 22:19:08 2021 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: udf_subr.c,v 1.160 2021/12/15 22:02:30 reinoud Exp $ */
+/* $NetBSD: udf_subr.c,v 1.161 2021/12/16 22:19:08 reinoud Exp $ */
 
 /*
  * Copyright (c) 2006, 2008 Reinoud Zandijk
@@ -29,7 +29,7 @@
 
 #include <sys/cdefs.h>
 #ifndef lint
-__KERNEL_RCSID(0, "$NetBSD: udf_subr.c,v 1.160 2021/12/15 22:02:30 reinoud Exp $");
+__KERNEL_RCSID(0, "$NetBSD: udf_subr.c,v 1.161 2021/12/16 22:19:08 reinoud Exp $");
 #endif /* not lint */
 
 
@@ -2765,10 +2765,11 @@
        struct icb_tag *icbtag;
        struct udf_oldvat_tail *oldvat_tl;
        struct udf_vat *vat;
+       struct regid *regid;
        uint64_t unique_id;
        uint32_t lb_size;
        uint8_t *raw_vat;
-       int filetype, error;
+       int vat_length, impl_use_len, filetype, error;
 
        KASSERT(vat_node);
        KASSERT(lvinfo);
@@ -2813,11 +2814,20 @@
                        sizeof(struct udf_oldvat_tail), ump->vat_entries * 4);
        } else {
                /* compose the VAT2 header */
+               vat_length = sizeof(struct udf_vat);
                vat = (struct udf_vat *) raw_vat;
-               memset(vat, 0, sizeof(struct udf_vat));
-
-               vat->header_len       = udf_rw16(152);  /* as per spec */
-               vat->impl_use_len     = udf_rw16(0);
+
+               error = udf_vat_read(vat_node, raw_vat, vat_length, 0);
+               if (error)
+                       goto errout;
+
+               impl_use_len = udf_rw16(vat->impl_use_len);
+               vat_length += impl_use_len;
+
+               error = udf_vat_read(vat_node, raw_vat, vat_length, 0);
+               if (error)
+                       goto errout;
+
                memmove(vat->logvol_id, ump->logical_vol->logvol_id, 128);
                vat->prev_vat         = udf_rw32(0xffffffff);
                vat->num_files        = lvinfo->num_files;
@@ -2826,9 +2836,20 @@
                vat->min_udf_writever = lvinfo->min_udf_writever;
                vat->max_udf_writever = lvinfo->max_udf_writever;
 
-               error = udf_vat_write(vat_node, raw_vat,
-                       sizeof(struct udf_vat), 0);
-       }
+               if (impl_use_len >= sizeof(struct regid)) {
+                       /* insert our implementation identification */
+                       memset(vat->data, 0, impl_use_len);
+                       regid = (struct regid *) vat->data;
+                       udf_set_regid(regid, IMPL_NAME);
+                       udf_add_app_regid(ump, regid);
+               } else {
+                       if (impl_use_len)
+                               memset(vat->data, 0, impl_use_len);
+                       vat->impl_use_len = 0;
+               }
+               error = udf_vat_write(vat_node, raw_vat, vat_length, 0);
+       }
+errout:
        free(raw_vat, M_TEMP);
 
        return error;   /* success! */
@@ -2997,7 +3018,7 @@
 
                /* definition */
                vat = (struct udf_vat *) raw_vat;
-               vat_offset  = vat->header_len;
+               vat_offset  = udf_rw16(vat->header_len);
                vat_entries = (vat_length - vat_offset)/4;
 
                assert(lvinfo);