Fixes an issue with x86 stack walking in the presence of doubly aligned frames

MSLaguana · MSLaguana · commit 706a951f34ea · 2017-12-12T15:23:34.000-08:00
This was in particular hitting the JSRT interface which had a doubly
aligned frame and caused crashes on stack walks.
diff --git a/lib/Runtime/Language/JavascriptStackWalker.cpp b/lib/Runtime/Language/JavascriptStackWalker.cpp
@@ -737,7 +737,7 @@ namespace Js
         }
 
         // If we're at the entry from a host frame, hop to the frame from which we left the script.
-        if (this->currentFrame.GetAddressOfInstructionPointer() == this->entryExitRecord->addrOfReturnAddrOfScriptEntryFunction)
+        if (AlignAndCheckAddressOfReturnAddressMatch(this->currentFrame.GetAddressOfInstructionPointer(), this->entryExitRecord->addrOfReturnAddrOfScriptEntryFunction))
         {
             BOOL hasCaller = this->entryExitRecord->hasCaller || this->forceFullWalk;
 
@@ -874,7 +874,7 @@ namespace Js
         return false;
     }
 
-    bool AlignAndCheckAddressOfReturnAddressMatch(void* addressOfReturnAddress, void* nativeLibraryEntryAddress)
+    bool JavascriptStackWalker::AlignAndCheckAddressOfReturnAddressMatch(void* addressOfReturnAddress, void* nativeLibraryEntryAddress)
     {
         return addressOfReturnAddress == nativeLibraryEntryAddress
 #if defined(_M_IX86)
@@ -883,7 +883,7 @@ namespace Js
             // return address offset by 4, 8, or 12.
             || (((uint)nativeLibraryEntryAddress - (uint)addressOfReturnAddress < 0x10) &&
                 *(void**)addressOfReturnAddress == *(void**)nativeLibraryEntryAddress
-               )
+                )
 #endif
             ;
     }
diff --git a/lib/Runtime/Language/JavascriptStackWalker.h b/lib/Runtime/Language/JavascriptStackWalker.h
@@ -231,6 +231,7 @@ namespace Js
         bool GetSourcePosition(const WCHAR** sourceFileName, ULONG* line, LONG* column);
 
         static bool TryIsTopJavaScriptFrameNative(ScriptContext* scriptContext, bool* istopFrameNative, bool ignoreLibraryCode = false);
+        static bool AlignAndCheckAddressOfReturnAddressMatch(void* addressOfReturnAddress, void* nativeLibraryEntryAddress);
 
 #if ENABLE_NATIVE_CODEGEN
         void ClearCachedInternalFrameInfo();

Original file line number	Diff line number	Diff line change
`@@ -737,7 +737,7 @@ namespace Js`
`737`	`737`	`}`
`738`	`738`
`739`	`739`	`// If we're at the entry from a host frame, hop to the frame from which we left the script.`
`740`		`- if (this->currentFrame.GetAddressOfInstructionPointer() == this->entryExitRecord->addrOfReturnAddrOfScriptEntryFunction)`
	`740`	`+ if (AlignAndCheckAddressOfReturnAddressMatch(this->currentFrame.GetAddressOfInstructionPointer(), this->entryExitRecord->addrOfReturnAddrOfScriptEntryFunction))`
`741`	`741`	`{`
`742`	`742`	`BOOL hasCaller = this->entryExitRecord->hasCaller \|\| this->forceFullWalk;`
`743`	`743`
`@@ -874,7 +874,7 @@ namespace Js`
`874`	`874`	`return false;`
`875`	`875`	`}`
`876`	`876`
`877`		`- bool AlignAndCheckAddressOfReturnAddressMatch(void* addressOfReturnAddress, void* nativeLibraryEntryAddress)`
	`877`	`+ bool JavascriptStackWalker::AlignAndCheckAddressOfReturnAddressMatch(void* addressOfReturnAddress, void* nativeLibraryEntryAddress)`
`878`	`878`	`{`
`879`	`879`	`return addressOfReturnAddress == nativeLibraryEntryAddress`
`880`	`880`	`#if defined(_M_IX86)`
`@@ -883,7 +883,7 @@ namespace Js`
`883`	`883`	`// return address offset by 4, 8, or 12.`
`884`	`884`	`\|\| (((uint)nativeLibraryEntryAddress - (uint)addressOfReturnAddress < 0x10) &&`
`885`	`885`	`(void)addressOfReturnAddress == (void**)nativeLibraryEntryAddress`
`886`		`- )`
	`886`	`+ )`
`887`	`887`	`#endif`
`888`	`888`	`;`
`889`	`889`	`}`