diff --git a/0001-vddk-Don-t-use-uninitialized-values-when-computing-p.patch b/0001-vddk-Don-t-use-uninitialized-values-when-computing-p.patch
new file mode 100644
index 0000000..142ac90
--- /dev/null
+++ b/0001-vddk-Don-t-use-uninitialized-values-when-computing-p.patch
@@ -0,0 +1,71 @@
+From 3578c005c8a2f479eb223bb89f7b0fba22d13766 Mon Sep 17 00:00:00 2001
+From: "Richard W.M. Jones" <rjones@redhat.com>
+Date: Tue, 22 Mar 2022 11:04:56 +0000
+Subject: [PATCH] vddk: Don't use uninitialized values when computing preferred
+ block size
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Commit 63d2dd2eb2 ("vddk: Export block size information for this
+plugin") tried to calculate the preferred block size from the logical
+and physical sector size reported by VDDK.  Unfortunately VDDK < 7’s
+VixDiskLib_GetInfo API returns a struct which does not contain
+these fields at all.  We knew about this already because the
+debug code does not print them, but the block size code uses
+them regardless of the VDDK version.
+
+The practical result of this error was that sometimes (depending on
+existing contents of memory) you would see the error:
+
+nbdkit: vddk[1]: error: plugin must set preferred block size to a power of 2
+
+Fix this by only using the fields when VDDK >= 7, and in earlier
+versions assuming VDDK’s normal sector size.
+
+Reported-by: Xiaodai Wang
+Fixes: commit 63d2dd2eb2c9980a07841fe84ec16844085a59c3
+Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2066655
+(cherry picked from commit 31bc5322b179545bef827022e1ae3b7859387b1b)
+---
+ plugins/vddk/vddk.c | 17 +++++++++++++++--
+ 1 file changed, 15 insertions(+), 2 deletions(-)
+
+diff --git a/plugins/vddk/vddk.c b/plugins/vddk/vddk.c
+index 5d31b073..51ef8f33 100644
+--- a/plugins/vddk/vddk.c
++++ b/plugins/vddk/vddk.c
+@@ -855,6 +855,7 @@ vddk_block_size (void *handle,
+ {
+   struct vddk_handle *h = handle;
+   VixDiskLibInfo *info;
++  uint32_t logicalSectorSize, physicalSectorSize;
+   struct command info_cmd = { .type = INFO, .ptr = &info };
+ 
+   if (send_command_and_wait (h, &info_cmd) == -1)
+@@ -862,8 +863,20 @@ vddk_block_size (void *handle,
+ 
+   /* VDDK can only serve whole 512 byte sectors. */
+   *minimum = VIXDISKLIB_SECTOR_SIZE;
+-  *preferred = MAX (MAX (info->logicalSectorSize, info->physicalSectorSize),
+-                    4096);
++
++  /* The logicalSectorSize and physicalSectorSize fields are only
++   * present in VDDK >= 7.  In earlier versions they will not be
++   * initialized and contain random values (beyond the end of the
++   * returned structure).  So compute sector sizes with this in mind.
++   */
++  logicalSectorSize = physicalSectorSize = VIXDISKLIB_SECTOR_SIZE;
++  if (library_version >= 7) {
++    logicalSectorSize = info->logicalSectorSize;
++    physicalSectorSize = info->physicalSectorSize;
++  }
++
++  *preferred = MAX (MAX (logicalSectorSize, physicalSectorSize), 4096);
++
+   *maximum = 0xffffffff;
+ 
+   VDDK_CALL_START (VixDiskLib_FreeInfo, "info")
+-- 
+2.31.1
+
diff --git a/nbdkit.spec b/nbdkit.spec
index 7e70f43..738025a 100644
--- a/nbdkit.spec
+++ b/nbdkit.spec
@@ -53,7 +53,7 @@ ExclusiveArch:  x86_64
 
 Name:           nbdkit
 Version:        1.30.1
-Release:        1%{?dist}
+Release:        2%{?dist}
 Summary:        NBD server
 
 License:        BSD
@@ -78,6 +78,7 @@ Source3:        copy-patches.sh
 # https://gitlab.com/nbdkit/nbdkit/-/commits/rhel-9.1/
 
 # Patches.
+Patch0001:     0001-vddk-Don-t-use-uninitialized-values-when-computing-p.patch
 
 # For automatic RPM Provides generation.
 # See: https://rpm-software-management.github.io/rpm/manual/dependency_generators.html
@@ -1177,13 +1178,15 @@ export LIBGUESTFS_TRACE=1
 
 
 %changelog
-* Tue Mar 15 2022 Richard W.M. Jones <rjones@redhat.com> - 1.30.1-1
+* Tue Mar 22 2022 Richard W.M. Jones <rjones@redhat.com> - 1.30.1-2
 - Rebase to new stable branch version 1.30.1
   resolves: rhbz#2059289
 - Add automatic provides generator and subpackage nbdkit-srpm-macros
   resolves: rhbz#2059291
 - New filters: blocksize-policy, protect, retry-request
 - Fix license of bash-completion subpackage
+- vddk: Fix use of uninitialized memory when computing block size
+  resolves: rhbz#2066655
 
 * Mon Jan 24 2022 Richard W.M. Jones <rjones@redhat.com> - 1.28.5-1
 - Rebase to new stable branch version 1.28.5