Verify memory address range validity in GDBRemoteCommunicationClient

Summary:
This aims to verify the validity of the response from the debugging
server in GDBRemoteCommunicationClient::GetMemoryRegionInfo. I was
working with ds2 (https://github.com/facebook/ds2) and encountered a bug
that caused the server's response to have a 'size' value of 0, which
caused lldb to behave incorrectly.

Reviewers: k8stone, labath, clayborg

Reviewed By: labath, clayborg

Subscribers: clayborg, sas, lldb-commits

Differential Revision: https://reviews.llvm.org/D31485

Change by Alex Langford <apl@fb.com>

llvm-svn: 299239

1 files changed, 12 insertions, 7 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
index 8423b7b3854..8aa78a4d5ed 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
@@ -1503,13 +1503,18 @@ Error GDBRemoteCommunicationClient::GetMemoryRegionInfo(
         }
       }
 
-      // We got a valid address range back but no permissions -- which means
-      // this is an unmapped page
-      if (region_info.GetRange().IsValid() && saw_permissions == false) {
-        region_info.SetReadable(MemoryRegionInfo::eNo);
-        region_info.SetWritable(MemoryRegionInfo::eNo);
-        region_info.SetExecutable(MemoryRegionInfo::eNo);
-        region_info.SetMapped(MemoryRegionInfo::eNo);
+      if (region_info.GetRange().IsValid()) {
+        // We got a valid address range back but no permissions -- which means
+        // this is an unmapped page
+        if (!saw_permissions) {
+          region_info.SetReadable(MemoryRegionInfo::eNo);
+          region_info.SetWritable(MemoryRegionInfo::eNo);
+          region_info.SetExecutable(MemoryRegionInfo::eNo);
+          region_info.SetMapped(MemoryRegionInfo::eNo);
+        }
+      } else {
+        // We got an invalid address range back
+        error.SetErrorString("Server returned invalid range");
       }
     } else {
       m_supports_memory_region_info = eLazyBoolNo;