[Qemu-devel] [PATCHv3] migration: catch unknown flags in ram_load

[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.

CC: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
---
v2->v3: - reworked last case in the if statement
        - added an error_report in case of an unknown flag [David]
v1->v2: rework loop from do ... while to while [Juan]

 arch_init.c |   34 +++++++++++++++-------------------
 1 file changed, 15 insertions(+), 19 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 9f1a174..93a1191 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 +1086,21 @@ 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) {
                 ret = -EINVAL;
-                goto done;
+                break;
             }
 
             ch = qemu_get_byte(f);
@@ -1114,7 +1111,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
             host = host_from_stream_offset(f, addr, flags);
             if (!host) {
                 ret = -EINVAL;
-                goto done;
+                break;
             }
 
             qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
@@ -1122,24 +1119,23 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
             void *host = host_from_stream_offset(f, addr, flags);
             if (!host) {
                 ret = -EINVAL;
-                goto done;
+                break;
             }
 
             if (load_xbzrle(f, addr, host) < 0) {
                 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)) {
+            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;
-- 
1.7.9.5