From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Wed, 12 Nov 2014 11:44:39 +0200
Subject: [PATCH] migration: fix parameter validation on ram load

During migration, the values read from migration stream during ram load
are not validated. Especially offset in host_from_stream_offset() and
also the length of the writes in the callers of said function.

To fix this, we need to make sure that the [offset, offset + length]
range fits into one of the allocated memory regions.

Validating addr < len should be sufficient since data seems to always be
managed in TARGET_PAGE_SIZE chunks.

Fixes: CVE-2014-7840

Note: follow-up patches add extra checks on each block->host access.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
(cherry picked from commit 0be839a2701369f669532ea5884c15bead1c6e08)

Conflicts:
	arch_init.c
---
 arch_init.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 23151b3..b6f7958 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -816,8 +816,8 @@ static inline void *host_from_stream_offset(QEMUFile *f,
     uint8_t len;
 
     if (flags & RAM_SAVE_FLAG_CONTINUE) {
-        if (!block) {
-            fprintf(stderr, "Ack, bad migration stream!\n");
+        if (!block || block->length <= offset) {
+            fprintf(stderr, "Ack, bad migration stream!");
             return NULL;
         }
 
@@ -829,8 +829,9 @@ static inline void *host_from_stream_offset(QEMUFile *f,
     id[len] = 0;
 
     QTAILQ_FOREACH(block, &ram_list.blocks, next) {
-        if (!strncmp(id, block->idstr, sizeof(id)))
+        if (!strncmp(id, block->idstr, sizeof(id)) && block->length > offset) {
             return memory_region_get_ram_ptr(block->mr) + offset;
+        }
     }
 
     fprintf(stderr, "Can't find block %s!\n", id);