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From: Laszlo Ersek <lersek@redhat.com>
Date: Thu, 12 Sep 2019 13:05:01 +0100
Subject: [PATCH 04/22] i386: fix regression parsing multiboot initrd modules
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RH-Author: Laszlo Ersek <lersek@redhat.com>
Message-id: <20190912130503.14094-5-lersek@redhat.com>
Patchwork-id: 90434
O-Subject: [RHEL-8.2.0 qemu-kvm PATCH 4/6] i386: fix regression parsing multiboot initrd modules
Bugzilla: 1749022
RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>

From: Daniel P. Berrangé <berrange@redhat.com>

The logic for parsing the multiboot initrd modules was messed up in

  commit 950c4e6c94b15cd0d8b63891dddd7a8dbf458e6a
  Author: Daniel P. Berrangé <berrange@redhat.com>
  Date:   Mon Apr 16 12:17:43 2018 +0100

    opts: don't silently truncate long option values

Causing the length to be undercounter, and the number of modules over
counted. It also passes NULL to get_opt_value() which was not robust
at accepting a NULL value.

RHEL8 notes:

- Context difference in "util/qemu-option.c", function get_opt_value();
  upstream has commit 5c99fa375da1 ("cutils: Provide strchrnul",
  2018-06-29), part of v3.0.0, but downstream lacks it. Harmless, because
  said upstream commit only refactors get_opt_value().

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20180514171913.17664-2-berrange@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Tested-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 6e3ad3f0e31b8e31c6c0769d0f474bcd9673e0e5)
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 hw/i386/multiboot.c | 3 +--
 util/qemu-option.c  | 4 +++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/hw/i386/multiboot.c b/hw/i386/multiboot.c
index 7a2953e..8e26545 100644
--- a/hw/i386/multiboot.c
+++ b/hw/i386/multiboot.c
@@ -292,8 +292,7 @@ int load_multiboot(FWCfgState *fw_cfg,
     cmdline_len += strlen(kernel_cmdline) + 1;
     if (initrd_filename) {
         const char *r = get_opt_value(initrd_filename, NULL);
-        cmdline_len += strlen(r) + 1;
-        mbs.mb_mods_avail = 1;
+        cmdline_len += strlen(initrd_filename) + 1;
         while (1) {
             mbs.mb_mods_avail++;
             r = get_opt_value(r, NULL);
diff --git a/util/qemu-option.c b/util/qemu-option.c
index ba44a08..a396d60 100644
--- a/util/qemu-option.c
+++ b/util/qemu-option.c
@@ -75,7 +75,9 @@ const char *get_opt_value(const char *p, char **value)
     size_t capacity = 0, length;
     const char *offset;
 
-    *value = NULL;
+    if (value) {
+        *value = NULL;
+    }
     while (1) {
         offset = strchr(p, ',');
         if (!offset) {
-- 
1.8.3.1