[Qemu-devel] [PATCH 1/4] migration: catch unknown flags in ram_load

[Juan Quintela <quintela@redhat.com>]

From: Peter Lieven <pl@kamp.de>

if a saved vm has unknown flags in the memory data qemu
currently simply ignores this flag and continues which
yields in an unpredictable result.

This patch catches all unknown flags and aborts the
loading of the vm. Additionally error reports are thrown
if the migration aborts abnormally.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 arch_init.c | 42 +++++++++++++++++++++++-------------------
 migration.c |  2 +-
 2 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 9f1a174..4ee782f 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -1041,17 +1041,15 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
 {
     ram_addr_t addr;
     int flags, ret = 0;
-    int error;
     static uint64_t seq_iter;

     seq_iter++;

     if (version_id != 4) {
         ret = -EINVAL;
-        goto done;
     }

-    do {
+    while (!ret) {
         addr = qemu_get_be64(f);

         flags = addr & ~TARGET_PAGE_MASK;
@@ -1079,7 +1077,6 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
                                          " in != " RAM_ADDR_FMT, id, length,
                                          block->length);
                             ret =  -EINVAL;
-                            goto done;
                         }
                         break;
                     }
@@ -1089,21 +1086,22 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
                     error_report("Unknown ramblock \"%s\", cannot "
                                  "accept migration", id);
                     ret = -EINVAL;
-                    goto done;
+                }
+                if (ret) {
+                    break;
                 }

                 total_ram_bytes -= length;
             }
-        }
-
-        if (flags & RAM_SAVE_FLAG_COMPRESS) {
+        } else if (flags & RAM_SAVE_FLAG_COMPRESS) {
             void *host;
             uint8_t ch;

             host = host_from_stream_offset(f, addr, flags);
             if (!host) {
+                error_report("Illegal RAM offset %" PRIx64, addr);
                 ret = -EINVAL;
-                goto done;
+                break;
             }

             ch = qemu_get_byte(f);
@@ -1113,33 +1111,39 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)

             host = host_from_stream_offset(f, addr, flags);
             if (!host) {
+                error_report("Illegal RAM offset %" PRIx64, addr);
                 ret = -EINVAL;
-                goto done;
+                break;
             }

             qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
         } else if (flags & RAM_SAVE_FLAG_XBZRLE) {
             void *host = host_from_stream_offset(f, addr, flags);
             if (!host) {
+                error_report("Illegal RAM offset %" PRIx64, addr);
                 ret = -EINVAL;
-                goto done;
+                break;
             }

             if (load_xbzrle(f, addr, host) < 0) {
+                error_report("Failed to decompress XBZRLE page at %" PRIx64,
+                             addr);
                 ret = -EINVAL;
-                goto done;
+                break;
             }
         } else if (flags & RAM_SAVE_FLAG_HOOK) {
             ram_control_load_hook(f, flags);
+        } else if (flags & RAM_SAVE_FLAG_EOS) {
+            /* normal exit */
+            break;
+        } else {
+            error_report("Unknown migration flags: %#x", flags);
+            ret = -EINVAL;
+            break;
         }
-        error = qemu_file_get_error(f);
-        if (error) {
-            ret = error;
-            goto done;
-        }
-    } while (!(flags & RAM_SAVE_FLAG_EOS));
+        ret = qemu_file_get_error(f);
+    }

-done:
     DPRINTF("Completed load of VM with exit code %d seq iteration "
             "%" PRIu64 "\n", ret, seq_iter);
     return ret;
diff --git a/migration.c b/migration.c
index 3fc03d6..3ebe9fb 100644
--- a/migration.c
+++ b/migration.c
@@ -98,7 +98,7 @@ static void process_incoming_migration_co(void *opaque)
     qemu_fclose(f);
     free_xbzrle_decoded_buf();
     if (ret < 0) {
-        fprintf(stderr, "load of migration failed\n");
+        error_report("load of migration failed: %s", strerror(-ret));
         exit(EXIT_FAILURE);
     }
     qemu_announce_self();
-- 
1.9.3