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From cfa472eb467f8e5139a2a7d30aa85c9affbccd4f Mon Sep 17 00:00:00 2001
From: Igor Mammedov <imammedo@redhat.com>
Date: Fri, 5 Oct 2018 12:59:47 +0100
Subject: [PATCH 6/6] memory: cleanup side effects of memory_region_init_foo()
 on failure

RH-Author: Igor Mammedov <imammedo@redhat.com>
Message-id: <1538744387-84898-1-git-send-email-imammedo@redhat.com>
Patchwork-id: 82391
O-Subject: [RHEL-8 qemu-kvm PATCH] memory: cleanup side effects of memory_region_init_foo() on failure
Bugzilla: 1600365
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RH-Acked-by: Pankaj Gupta <pagupta@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1600365
Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=18658506

if MemoryRegion intialization fails it's left in semi-initialized state,
where it's size is not 0 and attached as child to owner object.
And this leds to crash in following use-case:
    (monitor) object_add memory-backend-file,id=mem1,size=99999G,mem-path=/tmp/foo,discard-data=yes
    memory.c:2083: memory_region_get_ram_ptr: Assertion `mr->ram_block' failed
    Aborted (core dumped)
it happens due to assumption that memory region is intialized when
   memory_region_size() != 0
and therefore it's ok to access it in
   file_backend_unparent()
      if (memory_region_size() != 0)
          memory_region_get_ram_ptr()

which happens when object_add fails and unparents failed backend making
file_backend_unparent() access invalid memory region.

Fix it by making sure that memory_region_init_foo() APIs cleanup externally
visible side effects on failure (like set size to 0 and unparenting object)

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1536064777-42312-1-git-send-email-imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 1cd3d492624da399d66c4c3e6a5eabb8f96bb0a2)
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

Conflicts:
	memory.c
          due missing (cbfc01710 "memory, exec: switch file ram allocation functions to 'flags' parameters")
          not related to the patch signature mismatch of
           qemu_ram_alloc_from_file()/qemu_ram_alloc_from_fd()
---
 memory.c | 48 ++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 42 insertions(+), 6 deletions(-)

diff --git a/memory.c b/memory.c
index e70b64b..1a99b9c 100644
--- a/memory.c
+++ b/memory.c
@@ -1519,12 +1519,18 @@ void memory_region_init_ram_shared_nomigrate(MemoryRegion *mr,
                                              bool share,
                                              Error **errp)
 {
+    Error *err = NULL;
     memory_region_init(mr, owner, name, size);
     mr->ram = true;
     mr->terminates = true;
     mr->destructor = memory_region_destructor_ram;
-    mr->ram_block = qemu_ram_alloc(size, share, mr, errp);
+    mr->ram_block = qemu_ram_alloc(size, share, mr, &err);
     mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
+    if (err) {
+        mr->size = int128_zero();
+        object_unparent(OBJECT(mr));
+        error_propagate(errp, err);
+    }
 }
 
 void memory_region_init_resizeable_ram(MemoryRegion *mr,
@@ -1537,13 +1543,19 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr,
                                                        void *host),
                                        Error **errp)
 {
+    Error *err = NULL;
     memory_region_init(mr, owner, name, size);
     mr->ram = true;
     mr->terminates = true;
     mr->destructor = memory_region_destructor_ram;
     mr->ram_block = qemu_ram_alloc_resizeable(size, max_size, resized,
-                                              mr, errp);
+                                              mr, &err);
     mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
+    if (err) {
+        mr->size = int128_zero();
+        object_unparent(OBJECT(mr));
+        error_propagate(errp, err);
+    }
 }
 
 #ifdef __linux__
@@ -1556,13 +1568,19 @@ void memory_region_init_ram_from_file(MemoryRegion *mr,
                                       const char *path,
                                       Error **errp)
 {
+    Error *err = NULL;
     memory_region_init(mr, owner, name, size);
     mr->ram = true;
     mr->terminates = true;
     mr->destructor = memory_region_destructor_ram;
     mr->align = align;
-    mr->ram_block = qemu_ram_alloc_from_file(size, mr, share, path, errp);
+    mr->ram_block = qemu_ram_alloc_from_file(size, mr, share, path, &err);
     mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
+    if (err) {
+        mr->size = int128_zero();
+        object_unparent(OBJECT(mr));
+        error_propagate(errp, err);
+    }
 }
 
 void memory_region_init_ram_from_fd(MemoryRegion *mr,
@@ -1573,12 +1591,18 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr,
                                     int fd,
                                     Error **errp)
 {
+    Error *err = NULL;
     memory_region_init(mr, owner, name, size);
     mr->ram = true;
     mr->terminates = true;
     mr->destructor = memory_region_destructor_ram;
-    mr->ram_block = qemu_ram_alloc_from_fd(size, mr, share, fd, errp);
+    mr->ram_block = qemu_ram_alloc_from_fd(size, mr, share, fd, &err);
     mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
+    if (err) {
+        mr->size = int128_zero();
+        object_unparent(OBJECT(mr));
+        error_propagate(errp, err);
+    }
 }
 #endif
 
@@ -1629,13 +1653,19 @@ void memory_region_init_rom_nomigrate(MemoryRegion *mr,
                                       uint64_t size,
                                       Error **errp)
 {
+    Error *err = NULL;
     memory_region_init(mr, owner, name, size);
     mr->ram = true;
     mr->readonly = true;
     mr->terminates = true;
     mr->destructor = memory_region_destructor_ram;
-    mr->ram_block = qemu_ram_alloc(size, false, mr, errp);
+    mr->ram_block = qemu_ram_alloc(size, false, mr, &err);
     mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
+    if (err) {
+        mr->size = int128_zero();
+        object_unparent(OBJECT(mr));
+        error_propagate(errp, err);
+    }
 }
 
 void memory_region_init_rom_device_nomigrate(MemoryRegion *mr,
@@ -1646,6 +1676,7 @@ void memory_region_init_rom_device_nomigrate(MemoryRegion *mr,
                                              uint64_t size,
                                              Error **errp)
 {
+    Error *err = NULL;
     assert(ops);
     memory_region_init(mr, owner, name, size);
     mr->ops = ops;
@@ -1653,7 +1684,12 @@ void memory_region_init_rom_device_nomigrate(MemoryRegion *mr,
     mr->terminates = true;
     mr->rom_device = true;
     mr->destructor = memory_region_destructor_ram;
-    mr->ram_block = qemu_ram_alloc(size, false,  mr, errp);
+    mr->ram_block = qemu_ram_alloc(size, false,  mr, &err);
+    if (err) {
+        mr->size = int128_zero();
+        object_unparent(OBJECT(mr));
+        error_propagate(errp, err);
+    }
 }
 
 void memory_region_init_iommu(void *_iommu_mr,
-- 
1.8.3.1