Add patches from upstream stable-1.26 branch, fixing a virt-v2v crash

resolves: rhbz#1950632
2021-07-26 09:54:35 +01:00 · 2021-07-26 09:54:35 +01:00 · bc50933de3
commit bc50933de3
parent 99acada896
8 changed files with 689 additions and 1 deletions
--- a/0001-ocaml-Call-caml_shutdown-when-unloading-the-plugin.patch
+++ b/0001-ocaml-Call-caml_shutdown-when-unloading-the-plugin.patch
@ -0,0 +1,76 @@
 From 5a23c7cf3c5eccac6e6de775722bc1136a66be83 Mon Sep 17 00:00:00 2001
 From: "Richard W.M. Jones" <rjones@redhat.com>
 Date: Mon, 5 Jul 2021 17:54:45 +0100
 Subject: [PATCH 1/7] ocaml: Call caml_shutdown when unloading the plugin
 This has several useful effects (taken from the OCaml documentation):
 * Running the functions that were registered with "Stdlib.at_exit".
 * Triggering finalization of allocated custom blocks.  For example,
  "Stdlib.in_channel" and "Stdlib.out_channel" are represented by
  custom blocks that enclose file descriptors, which are to be
  released.
 * Unloading the dependent shared libraries that were loaded by the runtime,
  including "dynlink" plugins.
 * Freeing the memory blocks that were allocated by the runtime with
  "malloc".
 If the function is not present (for OCaml < 4.05) then we just skip
 this step.
 (cherry picked from commit 99140272a0675b3d123d2c42cb0a5ab73b09fba2)
 ---
 configure.ac           | 18 ++++++++++++++++++
 plugins/ocaml/plugin.c |  4 ++++
 2 files changed, 22 insertions(+)
 diff --git a/configure.ac b/configure.ac
 index 9b171b7e..a7c4c8d3 100644
 --- a/configure.ac
 +++ b/configure.ac
@@ -857,6 +857,24 @@ EOF
     rm -f conftest.c conftest.o
 ])
 +dnl Check if OCaml has caml_shutdown (added 2014).
 +AS_IF([test "x$OCAMLC" != "xno" && test "x$OCAMLFIND" != "xno" && \
 +       test "x$enable_ocaml" = "xyes"],[
 +    AC_MSG_CHECKING([for caml_shutdown])
 +    cat >conftest.c <<'EOF'
 +#include <caml/callback.h>
 +int main () { char *p = (void *) caml_shutdown; return 0; }
 +EOF
 +    AS_IF([$OCAMLC conftest.c >&AS_MESSAGE_LOG_FD 2>&1],[
 +        AC_MSG_RESULT([yes])
 +        AC_DEFINE([HAVE_CAML_SHUTDOWN],[1],
 +                  [caml_shutdown found at compile time.])
 +    ],[
 +        AC_MSG_RESULT([no])
 +    ])
 +    rm -f conftest.c conftest.o
 +])
 +
 dnl For developing plugins in Rust, optional.
 AC_CHECK_PROG([CARGO],[cargo],[cargo],[no])
 AC_ARG_ENABLE([rust],
 diff --git a/plugins/ocaml/plugin.c b/plugins/ocaml/plugin.c
 index 00959cb6..9d7d72ad 100644
 --- a/plugins/ocaml/plugin.c
 +++ b/plugins/ocaml/plugin.c
@@ -131,6 +131,10 @@ unload_wrapper (void)
   free ((char *) plugin.config_help);
   remove_roots ();
 +
 +#ifdef HAVE_CAML_SHUTDOWN
 +  caml_shutdown ();
 +#endif
 }
 static void
 -- 
 2.32.0
--- a/0002-ocaml-Fix-valgrinding-by-only-ignoring-caml_stat_all.patch
+++ b/0002-ocaml-Fix-valgrinding-by-only-ignoring-caml_stat_all.patch
@ -0,0 +1,39 @@
 From 397b7b245aee178b2683de8a34847843f658b43d Mon Sep 17 00:00:00 2001
 From: "Richard W.M. Jones" <rjones@redhat.com>
 Date: Mon, 5 Jul 2021 18:00:28 +0100
 Subject: [PATCH 2/7] ocaml: Fix valgrinding by only ignoring caml_stat_alloc*
 functions
 These are meant to be "static" so are not freed by design.  Other
 allocations should all be freed, especially now that we are calling
 caml_shutdown.
 (cherry picked from commit 875a5056758dca754225f49516a0f4c8e788ac94)
 ---
 valgrind/ocaml.suppressions | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
 diff --git a/valgrind/ocaml.suppressions b/valgrind/ocaml.suppressions
 index f74b0943..a2b7fc60 100644
 --- a/valgrind/ocaml.suppressions
 +++ b/valgrind/ocaml.suppressions
@@ -29,11 +29,12 @@
 # OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 # SUCH DAMAGE.
 -# OCaml, by design, doesn't bother to free the major heap before
 -# calling exit.  Ignore that leak.
 +# OCaml caml_stat_* allocations are meant to be "static" so OCaml will
 +# never free them by design.  See the OCaml manual, chapter
 +# "Interfacing C with OCaml".
 {
 -   ocaml_heap_leak
 +   ocaml_stat_allocations
    Memcheck:Leak
    ...
 -   fun:caml_alloc_for_heap
 +   fun:caml_stat_alloc*
 }
 -- 
 2.32.0
--- a/0003-ocaml-tests-Actually-call-.get_ready-method-in-test-.patch
+++ b/0003-ocaml-tests-Actually-call-.get_ready-method-in-test-.patch
@ -0,0 +1,29 @@
 From 4efeffd80a5e85abf5603f20631910b2ef180317 Mon Sep 17 00:00:00 2001
 From: "Richard W.M. Jones" <rjones@redhat.com>
 Date: Tue, 13 Jul 2021 16:50:16 +0100
 Subject: [PATCH 3/7] ocaml: tests: Actually call .get_ready method in test
 plugin
 It was added in a previous commit, but never called.
 Fixes: commit d52d0adf3d395f98f0fb4cd06044cc6dc7aeaef0
 (cherry picked from commit 156aa8337e5d1886c296a94de631b01c10f1bc78)
 ---
 tests/test_ocaml_plugin.ml | 1 +
 1 file changed, 1 insertion(+)
 diff --git a/tests/test_ocaml_plugin.ml b/tests/test_ocaml_plugin.ml
 index 2bbaa218..fee8528e 100644
 --- a/tests/test_ocaml_plugin.ml
 +++ b/tests/test_ocaml_plugin.ml
@@ -99,6 +99,7 @@ let plugin = {
     version         = NBDKit.version ();
     load            = Some load;
 +    get_ready       = Some get_ready;
     unload          = Some unload;
     config          = Some config;
     config_complete = Some config_complete;
 -- 
 2.32.0
--- a/0004-ocaml-Rearrange-the-callbacks.patch
+++ b/0004-ocaml-Rearrange-the-callbacks.patch
@ -0,0 +1,315 @@
 From 1610c0865534819eccefec55fd2d751843bb6d64 Mon Sep 17 00:00:00 2001
 From: "Richard W.M. Jones" <rjones@redhat.com>
 Date: Tue, 13 Jul 2021 16:15:45 +0100
 Subject: [PATCH 4/7] ocaml: Rearrange the callbacks
 Just refactoring.
 (cherry picked from commit e54e16e81c51dcbb16d70d83c5b0403babdf5f99)
 ---
 plugins/ocaml/NBDKit.mli   | 31 +++++++++--------
 plugins/ocaml/callbacks.h  | 34 +++++++++----------
 plugins/ocaml/NBDKit.ml    | 68 ++++++++++++++++++--------------------
 tests/test_ocaml_plugin.ml |  9 ++---
 4 files changed, 72 insertions(+), 70 deletions(-)
 diff --git a/plugins/ocaml/NBDKit.mli b/plugins/ocaml/NBDKit.mli
 index ac4b0cbc..cda09f44 100644
 --- a/plugins/ocaml/NBDKit.mli
 +++ b/plugins/ocaml/NBDKit.mli
@@ -69,33 +69,31 @@ type thread_model =
     The ['a] parameter is the handle type returned by your
     [open_connection] method and passed back to all connected calls. *)
 type 'a plugin = {
 -  name : string;                                  (* required *)
 +  (* Plugin description. *)
 +  name : string;                (** required field *)
   longname : string;
   version : string;
   description : string;
 +  (* Plugin lifecycle. *)
   load : (unit -> unit) option;
 +  get_ready : (unit -> unit) option;
 +  after_fork : (unit -> unit) option;
   unload : (unit -> unit) option;
 -  dump_plugin : (unit -> unit) option;
 -
 +  (* Plugin configuration. *)
   config : (string -> string -> unit) option;
   config_complete : (unit -> unit) option;
   config_help : string;
   thread_model : (unit -> thread_model) option;
 -  get_ready : (unit -> unit) option;
 -  after_fork : (unit -> unit) option;
 -
 +  (* Connection lifecycle. *)
   preconnect : (bool -> unit) option;
 -  list_exports : (bool -> bool -> export list) option;
 -  default_export : (bool -> bool -> string) option;
 -  open_connection : (bool -> 'a) option;          (* required *)
 +  open_connection : (bool -> 'a) option; (** required field *)
   close : ('a -> unit) option;
 -  get_size : ('a -> int64) option;                (* required *)
 -  export_description : ('a -> string) option;
 -
 +  (* NBD negotiation. *)
 +  get_size : ('a -> int64) option; (** required field *)
   can_cache : ('a -> cache_flag) option;
   can_extents : ('a -> bool) option;
   can_fast_zero : ('a -> bool) option;
@@ -107,13 +105,20 @@ type 'a plugin = {
   can_zero : ('a -> bool) option;
   is_rotational : ('a -> bool) option;
 -  pread : ('a -> int32 -> int64 -> flags -> string) option;  (* required *)
 +  (* Serving data. *)
 +  pread : ('a -> int32 -> int64 -> flags -> string) option; (* required field *)
   pwrite : ('a -> string -> int64 -> flags -> unit) option;
   flush : ('a -> flags -> unit) option;
   trim : ('a -> int32 -> int64 -> flags -> unit) option;
   zero : ('a -> int32 -> int64 -> flags -> unit) option;
   extents : ('a -> int32 -> int64 -> flags -> extent list) option;
   cache : ('a -> int32 -> int64 -> flags -> unit) option;
 +
 +  (* Miscellaneous. *)
 +  dump_plugin : (unit -> unit) option;
 +  list_exports : (bool -> bool -> export list) option;
 +  default_export : (bool -> bool -> string) option;
 +  export_description : ('a -> string) option;
 }
 (** The plugin with all fields set to [None], so you can write
 diff --git a/plugins/ocaml/callbacks.h b/plugins/ocaml/callbacks.h
 index 7171ef21..4d29fb73 100644
 --- a/plugins/ocaml/callbacks.h
 +++ b/plugins/ocaml/callbacks.h
@@ -33,21 +33,8 @@
 /* This is not a header file.  It is included at various places in
  * plugin.c as a convenient way to define per-callback things.
  */
 -CB(load)
 -CB(unload)
 -CB(dump_plugin)
 -CB(config)
 -CB(config_complete)
 -CB(thread_model)
 -CB(get_ready)
 CB(after_fork)
 -CB(preconnect)
 -CB(list_exports)
 -CB(default_export)
 -CB(open)
 -CB(close)
 -CB(get_size)
 -CB(export_description)
 +CB(cache)
 CB(can_cache)
 CB(can_extents)
 CB(can_fast_zero)
@@ -57,11 +44,24 @@ CB(can_multi_conn)
 CB(can_trim)
 CB(can_write)
 CB(can_zero)
 +CB(close)
 +CB(config)
 +CB(config_complete)
 +CB(default_export)
 +CB(dump_plugin)
 +CB(export_description)
 +CB(extents)
 +CB(flush)
 +CB(get_ready)
 +CB(get_size)
 CB(is_rotational)
 +CB(list_exports)
 +CB(load)
 +CB(open)
 CB(pread)
 +CB(preconnect)
 CB(pwrite)
 -CB(flush)
 +CB(thread_model)
 CB(trim)
 +CB(unload)
 CB(zero)
 -CB(extents)
 -CB(cache)
 diff --git a/plugins/ocaml/NBDKit.ml b/plugins/ocaml/NBDKit.ml
 index cdc3bc58..529618d2 100644
 --- a/plugins/ocaml/NBDKit.ml
 +++ b/plugins/ocaml/NBDKit.ml
@@ -65,27 +65,20 @@ type 'a plugin = {
   description : string;
   load : (unit -> unit) option;
 +  get_ready : (unit -> unit) option;
 +  after_fork : (unit -> unit) option;
   unload : (unit -> unit) option;
 -  dump_plugin : (unit -> unit) option;
 -
   config : (string -> string -> unit) option;
   config_complete : (unit -> unit) option;
   config_help : string;
   thread_model : (unit -> thread_model) option;
 -  get_ready : (unit -> unit) option;
 -  after_fork : (unit -> unit) option;
 -
   preconnect : (bool -> unit) option;
 -  list_exports : (bool -> bool -> export list) option;
 -  default_export : (bool -> bool -> string) option;
   open_connection : (bool -> 'a) option;
   close : ('a -> unit) option;
   get_size : ('a -> int64) option;
 -  export_description : ('a -> string) option;
 -
   can_cache : ('a -> cache_flag) option;
   can_extents : ('a -> bool) option;
   can_fast_zero : ('a -> bool) option;
@@ -104,6 +97,11 @@ type 'a plugin = {
   zero : ('a -> int32 -> int64 -> flags -> unit) option;
   extents : ('a -> int32 -> int64 -> flags -> extent list) option;
   cache : ('a -> int32 -> int64 -> flags -> unit) option;
 +
 +  dump_plugin : (unit -> unit) option;
 +  list_exports : (bool -> bool -> export list) option;
 +  default_export : (bool -> bool -> string) option;
 +  export_description : ('a -> string) option;
 }
 let default_callbacks = {
@@ -113,27 +111,20 @@ let default_callbacks = {
   description = "";
   load = None;
 +  get_ready = None;
 +  after_fork = None;
   unload = None;
 -  dump_plugin = None;
 -
   config = None;
   config_complete = None;
   config_help = "";
   thread_model = None;
 -  get_ready = None;
 -  after_fork = None;
 -
   preconnect = None;
 -  list_exports = None;
 -  default_export = None;
   open_connection = None;
   close = None;
   get_size = None;
 -  export_description = None;
 -
   can_cache = None;
   can_extents = None;
   can_fast_zero = None;
@@ -152,6 +143,11 @@ let default_callbacks = {
   zero = None;
   extents = None;
   cache = None;
 +
 +  dump_plugin = None;
 +  list_exports = None;
 +  default_export = None;
 +  export_description = None;
 }
 external set_name : string -> unit = "ocaml_nbdkit_set_name" "noalloc"
@@ -186,21 +182,8 @@ let register_plugin plugin =
   if plugin.config_help <> "" then set_config_help plugin.config_help;
   let may f = function None -> () | Some a -> f a in
 -  may (set_field "load") plugin.load;
 -  may (set_field "unload") plugin.unload;
 -  may (set_field "dump_plugin") plugin.dump_plugin;
 -  may (set_field "config") plugin.config;
 -  may (set_field "config_complete") plugin.config_complete;
 -  may (set_field "thread_model") plugin.thread_model;
 -  may (set_field "get_ready") plugin.get_ready;
   may (set_field "after_fork") plugin.after_fork;
 -  may (set_field "preconnect") plugin.preconnect;
 -  may (set_field "list_exports") plugin.list_exports;
 -  may (set_field "default_export") plugin.default_export;
 -  may (set_field "open") plugin.open_connection;
 -  may (set_field "close") plugin.close;
 -  may (set_field "get_size") plugin.get_size;
 -  may (set_field "export_description") plugin.export_description;
 +  may (set_field "cache") plugin.cache;
   may (set_field "can_cache") plugin.can_cache;
   may (set_field "can_extents") plugin.can_extents;
   may (set_field "can_fast_zero") plugin.can_fast_zero;
@@ -210,14 +193,27 @@ let register_plugin plugin =
   may (set_field "can_trim") plugin.can_trim;
   may (set_field "can_write") plugin.can_write;
   may (set_field "can_zero") plugin.can_zero;
 +  may (set_field "close") plugin.close;
 +  may (set_field "config") plugin.config;
 +  may (set_field "config_complete") plugin.config_complete;
 +  may (set_field "default_export") plugin.default_export;
 +  may (set_field "dump_plugin") plugin.dump_plugin;
 +  may (set_field "export_description") plugin.export_description;
 +  may (set_field "extents") plugin.extents;
 +  may (set_field "flush") plugin.flush;
 +  may (set_field "get_ready") plugin.get_ready;
 +  may (set_field "get_size") plugin.get_size;
   may (set_field "is_rotational") plugin.is_rotational;
 +  may (set_field "list_exports") plugin.list_exports;
 +  may (set_field "load") plugin.load;
 +  may (set_field "open") plugin.open_connection;
   may (set_field "pread") plugin.pread;
 +  may (set_field "preconnect") plugin.preconnect;
   may (set_field "pwrite") plugin.pwrite;
 -  may (set_field "flush") plugin.flush;
 +  may (set_field "thread_model") plugin.thread_model;
   may (set_field "trim") plugin.trim;
 -  may (set_field "zero") plugin.zero;
 -  may (set_field "extents") plugin.extents;
 -  may (set_field "cache") plugin.cache
 +  may (set_field "unload") plugin.unload;
 +  may (set_field "zero") plugin.zero
 (* Bindings to nbdkit server functions. *)
 diff --git a/tests/test_ocaml_plugin.ml b/tests/test_ocaml_plugin.ml
 index fee8528e..00a65a75 100644
 --- a/tests/test_ocaml_plugin.ml
 +++ b/tests/test_ocaml_plugin.ml
@@ -101,19 +101,20 @@ let plugin = {
     load            = Some load;
     get_ready       = Some get_ready;
     unload          = Some unload;
 +
     config          = Some config;
     config_complete = Some config_complete;
 +    thread_model    = Some thread_model;
     open_connection = Some open_connection;
     close           = Some close;
 -    list_exports    = Some list_exports;
 -    default_export  = Some default_export;
     get_size        = Some get_size;
     pread           = Some pread;
     pwrite          = Some pwrite;
 -
     extents         = Some extents;
 -    thread_model    = Some thread_model;
 +
 +    list_exports    = Some list_exports;
 +    default_export  = Some default_export;
 }
 let () = NBDKit.register_plugin plugin
 -- 
 2.32.0
--- a/0005-ocaml-Fix-comment-on-plugin-.pread-field.patch
+++ b/0005-ocaml-Fix-comment-on-plugin-.pread-field.patch
@ -0,0 +1,29 @@
 From 229f106d65e2a54aa21afde9182b0e110a83b0df Mon Sep 17 00:00:00 2001
 From: "Richard W.M. Jones" <rjones@redhat.com>
 Date: Thu, 15 Jul 2021 20:41:03 +0100
 Subject: [PATCH 5/7] ocaml: Fix comment on plugin .pread field
 Incorrectly updated in earlier commit.
 Fixes: commit e54e16e81c51dcbb16d70d83c5b0403babdf5f99
 (cherry picked from commit b42144fc3eb6869d3a3424036877f206c6c5f2b9)
 ---
 plugins/ocaml/NBDKit.mli | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 diff --git a/plugins/ocaml/NBDKit.mli b/plugins/ocaml/NBDKit.mli
 index cda09f44..0f7b87e9 100644
 --- a/plugins/ocaml/NBDKit.mli
 +++ b/plugins/ocaml/NBDKit.mli
@@ -106,7 +106,7 @@ type 'a plugin = {
   is_rotational : ('a -> bool) option;
   (* Serving data. *)
 -  pread : ('a -> int32 -> int64 -> flags -> string) option; (* required field *)
 +  pread : ('a -> int32 -> int64 -> flags -> string) option;(** required field *)
   pwrite : ('a -> string -> int64 -> flags -> unit) option;
   flush : ('a -> flags -> unit) option;
   trim : ('a -> int32 -> int64 -> flags -> unit) option;
 -- 
 2.32.0
--- a/0006-docs-Correct-selinux-label-example.patch
+++ b/0006-docs-Correct-selinux-label-example.patch
@ -0,0 +1,40 @@
 From 8c86f8bbc326ff1578989a03b3c98b06634f62c1 Mon Sep 17 00:00:00 2001
 From: "Richard W.M. Jones" <rjones@redhat.com>
 Date: Thu, 22 Jul 2021 16:31:34 +0100
 Subject: [PATCH 6/7] docs: Correct --selinux-label example
 The actual label you should use for the internal socket is
 system_u:object_r:svirt_socket_t:s0 (not svirt_t).
 The filesystem label is different and was not documented before, so
 this is added.
 See also:
 https://bugzilla.redhat.com/show_bug.cgi?id=1984938
 (cherry picked from commit 835762d1c68e30f650032bc8d8280e6140d8e46f)
 ---
 docs/nbdkit.pod | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
 diff --git a/docs/nbdkit.pod b/docs/nbdkit.pod
 index 68399eca..5b679895 100644
 --- a/docs/nbdkit.pod
 +++ b/docs/nbdkit.pod
@@ -377,9 +377,11 @@ socket.
 The common — perhaps only — use of this option is to allow libvirt
 guests which are using SELinux and sVirt confinement to access nbdkit
 -Unix domain sockets:
 +Unix domain sockets.  The example below shows how to do this.  Note
 +that the socket and filesystem labels are different.
 - nbdkit --selinux-label system_u:object_r:svirt_t:s0 ...
 + nbdkit -U /tmp/sock --selinux-label=system_u:object_r:svirt_socket_t:s0 ...
 + chcon system_u:object_r:svirt_image_t:s0 /tmp/sock
 =item B<--swap>
 -- 
 2.32.0
--- a/0007-cow-Fix-assert-failure-in-cow_extents.patch
+++ b/0007-cow-Fix-assert-failure-in-cow_extents.patch
@ -0,0 +1,148 @@
 From c0c0728f40466cf4a8ab4868002e331df6d85b1e Mon Sep 17 00:00:00 2001
 From: "Richard W.M. Jones" <rjones@redhat.com>
 Date: Sat, 24 Jul 2021 13:30:55 +0100
 Subject: [PATCH 7/7] cow: Fix assert failure in cow_extents
 $ nbdkit sparse-random 4G --filter=cow --run 'nbdinfo --map $uri'
 nbdkit: cow.c:591: cow_extents: Assertion `count > 0' failed.
 nbdinfo calls us with count = 0xfffffe00 [1] stored in a 32 bit
 quantity.  This was rounded up to the next block boundary and so
 overflows (count becomes 0, hence the assertion).
 Use a 64 bit variable for count to allow rounding up.  This requires
 further changes as a further 32 bit variable must not be allowed to
 overflow.
 This also adds a regression test.
 [1] UINT32_MAX - 512 + 1 from:
 https://gitlab.com/nbdkit/libnbd/-/blob/c55c5d9960809efd27cd044d007a33ea1636f4b0/info/map.c#L64
 (cherry picked from commit 4d66ab72b29fc56190c7a6368eff3a6ba94c0f9f)
 ---
 tests/Makefile.am               |  2 ++
 filters/cow/cow.c               | 16 +++++++++---
 tests/test-cow-extents-large.sh | 46 +++++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+), 3 deletions(-)
 create mode 100755 tests/test-cow-extents-large.sh
 diff --git a/tests/Makefile.am b/tests/Makefile.am
 index e0b31ba9..9630205d 100644
 --- a/tests/Makefile.am
 +++ b/tests/Makefile.am
@@ -1402,6 +1402,7 @@ TESTS += \
 	test-cow.sh \
 	test-cow-extents1.sh \
 	test-cow-extents2.sh \
 +	test-cow-extents-large.sh \
 	test-cow-unaligned.sh \
 	$(NULL)
 endif
@@ -1410,6 +1411,7 @@ EXTRA_DIST += \
 	test-cow.sh \
 	test-cow-extents1.sh \
 	test-cow-extents2.sh \
 +	test-cow-extents-large.sh \
 	test-cow-null.sh \
 	test-cow-unaligned.sh \
 	$(NULL)
 diff --git a/filters/cow/cow.c b/filters/cow/cow.c
 index 83844845..3bd09399 100644
 --- a/filters/cow/cow.c
 +++ b/filters/cow/cow.c
@@ -571,19 +571,23 @@ cow_cache (nbdkit_next *next,
 /* Extents. */
 static int
 cow_extents (nbdkit_next *next,
 -             void *handle, uint32_t count, uint64_t offset, uint32_t flags,
 +             void *handle, uint32_t count32, uint64_t offset, uint32_t flags,
              struct nbdkit_extents *extents, int *err)
 {
   const bool can_extents = next->can_extents (next);
   const bool req_one = flags & NBDKIT_FLAG_REQ_ONE;
 +  uint64_t count = count32;
   uint64_t end;
   uint64_t blknum;
 -  /* To make this easier, align the requested extents to whole blocks. */
 +  /* To make this easier, align the requested extents to whole blocks.
 +   * Note that count is a 64 bit variable containing at most a 32 bit
 +   * value so rounding up is safe here.
 +   */
   end = offset + count;
   offset = ROUND_DOWN (offset, BLKSIZE);
   end = ROUND_UP (end, BLKSIZE);
 -  count  = end - offset;
 +  count = end - offset;
   blknum = offset / BLKSIZE;
   assert (IS_ALIGNED (offset, BLKSIZE));
@@ -628,6 +632,12 @@ cow_extents (nbdkit_next *next,
        * as we can.
        */
       for (;;) {
 +        /* nbdkit_extents_full cannot read more than a 32 bit range
 +         * (range_count), but count is a 64 bit quantity, so don't
 +         * overflow range_count here.
 +         */
 +        if (range_count >= UINT32_MAX - BLKSIZE + 1) break;
 +
         blknum++;
         offset += BLKSIZE;
         count -= BLKSIZE;
 diff --git a/tests/test-cow-extents-large.sh b/tests/test-cow-extents-large.sh
 new file mode 100755
 index 00000000..ea981dcb
 --- /dev/null
 +++ b/tests/test-cow-extents-large.sh
@@ -0,0 +1,46 @@
 +#!/usr/bin/env bash
 +# nbdkit
 +# Copyright (C) 2018-2021 Red Hat Inc.
 +#
 +# Redistribution and use in source and binary forms, with or without
 +# modification, are permitted provided that the following conditions are
 +# met:
 +#
 +# * Redistributions of source code must retain the above copyright
 +# notice, this list of conditions and the following disclaimer.
 +#
 +# * Redistributions in binary form must reproduce the above copyright
 +# notice, this list of conditions and the following disclaimer in the
 +# documentation and/or other materials provided with the distribution.
 +#
 +# * Neither the name of Red Hat nor the names of its contributors may be
 +# used to endorse or promote products derived from this software without
 +# specific prior written permission.
 +#
 +# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
 +# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 +# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 +# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
 +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 +# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 +# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 +# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 +# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 +# SUCH DAMAGE.
 +
 +# Regression test of an earlier overflow in cow_extents.
 +# https://listman.redhat.com/archives/libguestfs/2021-July/msg00037.html
 +
 +source ./functions.sh
 +set -e
 +set -x
 +
 +requires_filter cow
 +requires_plugin sparse-random
 +requires nbdinfo --version
 +
 +for size in 0 3G 4G 5G 8G; do
 +    nbdkit -U - sparse-random $size --filter=cow --run 'nbdinfo --map $uri'
 +done
 -- 
 2.32.0
--- a/nbdkit.spec
+++ b/nbdkit.spec
@ -51,7 +51,7 @@ ExclusiveArch:  x86_64
 Name:           nbdkit
 Version:        1.26.2
-Release:        1%{?dist}
+Release:        1%{?dist}.1
 Summary:        NBD server
 License:        BSD
@ -72,6 +72,15 @@ Source2:        libguestfs.keyring
 # Maintainer script which helps with handling patches.
 Source3:        copy-patches.sh
 # Patches in upstream stable-1.26 branch.
 Patch0001:      0001-ocaml-Call-caml_shutdown-when-unloading-the-plugin.patch
 Patch0002:      0002-ocaml-Fix-valgrinding-by-only-ignoring-caml_stat_all.patch
 Patch0003:      0003-ocaml-tests-Actually-call-.get_ready-method-in-test-.patch
 Patch0004:      0004-ocaml-Rearrange-the-callbacks.patch
 Patch0005:      0005-ocaml-Fix-comment-on-plugin-.pread-field.patch
 Patch0006:      0006-docs-Correct-selinux-label-example.patch
 Patch0007:      0007-cow-Fix-assert-failure-in-cow_extents.patch
 BuildRequires: make
 %if 0%{patches_touch_autotools}
 BuildRequires:  autoconf, automake, libtool
@ -1241,6 +1250,9 @@ export LIBGUESTFS_TRACE=1
 %changelog
 * Mon Jul 26 2021 Richard W.M. Jones <rjones@redhat.com> - 1.26.2-1.1
 - Add patches from upstream stable-1.26 branch, fixing a virt-v2v crash
 * Mon Jul 05 2021 Richard W.M. Jones <rjones@redhat.com> - 1.26.2-1
 - New upstream stable version 1.26.2.