[release-branch.go1.15] runtime: non-strict InlTreeIndex lookup in expandFinalInlineFrame

This is a follow-up to golang.org/cl/301369, which made the same change
in Frames.Next. The same logic applies here: a profile stack may have
been truncated at an invalid PC provided by cgoTraceback.
expandFinalInlineFrame will then try to lookup the inline tree and
crash.

The same fix applies as well: upon encountering a bad PC, simply leave
it as-is and move on.

For #44971
For #45480
Fixes #45481

Change-Id: I2823c67a1f3425466b05384cc6d30f5fc8ee6ddc
Reviewed-on: https://go-review.googlesource.com/c/go/+/309109
Reviewed-by: Michael Knyszek <[email protected]>
Trust: Michael Pratt <[email protected]>
(cherry picked from commit aad13cb)
Reviewed-on: https://go-review.googlesource.com/c/go/+/309550
Run-TryBot: Michael Pratt <[email protected]>
Reviewed-by: Cherry Zhang <[email protected]>
TryBot-Result: Go Bot <[email protected]>

Author: prattmic

src/runtime/symtab.go

@@ -185,7 +185,9 @@ func runtime_expandFinalInlineFrame(stk []uintptr) []uintptr {
 	var cache pcvalueCache
 	inltree := (*[1 << 20]inlinedCall)(inldata)
 	for {
-		ix := pcdatavalue(f, _PCDATA_InlTreeIndex, tracepc, &cache)
+		// Non-strict as cgoTraceback may have added bogus PCs
+		// with a valid funcInfo but invalid PCDATA.
+		ix := pcdatavalue1(f, _PCDATA_InlTreeIndex, tracepc, &cache, false)
 		if ix < 0 {
 			break
 		}