debug/gocore: defend againt partial DWARF records
Make sure we don't crash if AttrField returns nil.
I needed a few of these fixed to read 1.10 core dumps.
Change-Id: I410cdf4a9a524c12c4f77c75bbeba35ca007bcb6
Reviewed-on: https://go-review.googlesource.com/100056
Reviewed-by: Heschi Kreinick <heschi@google.com>
diff --git a/gocore/dwarf.go b/gocore/dwarf.go
index cff0097..16473b2 100644
--- a/gocore/dwarf.go
+++ b/gocore/dwarf.go
@@ -350,7 +350,11 @@
if e.Tag != dwarf.TagConstant {
continue
}
- name := e.AttrField(dwarf.AttrName).Val.(string)
+ f := e.AttrField(dwarf.AttrName)
+ if f == nil {
+ continue
+ }
+ name := f.Val.(string)
if !strings.HasPrefix(name, "runtime.") {
continue
}
@@ -377,7 +381,11 @@
if e.Tag != dwarf.TagVariable {
continue
}
- loc := e.AttrField(dwarf.AttrLocation).Val.([]byte)
+ f := e.AttrField(dwarf.AttrLocation)
+ if f == nil {
+ continue
+ }
+ loc := f.Val.([]byte)
if len(loc) == 0 || loc[0] != _DW_OP_addr {
continue
}
@@ -392,15 +400,23 @@
// TODO: keep roots around anyway?
continue
}
- dt, err := d.Type(e.AttrField(dwarf.AttrType).Val.(dwarf.Offset))
+ f = e.AttrField(dwarf.AttrType)
+ if f == nil {
+ continue
+ }
+ dt, err := d.Type(f.Val.(dwarf.Offset))
if err != nil {
panic(err)
}
if _, ok := dt.(*dwarf.UnspecifiedType); ok {
continue // Ignore markers like data/edata.
}
+ nf := e.AttrField(dwarf.AttrName)
+ if nf == nil {
+ continue
+ }
p.globals = append(p.globals, &Root{
- Name: e.AttrField(dwarf.AttrName).Val.(string),
+ Name: nf.Val.(string),
Addr: a,
Type: p.dwarfMap[dt],
Frame: nil,
@@ -420,8 +436,13 @@
r := d.Reader()
for e, err := r.Next(); e != nil && err == nil; e, err = r.Next() {
if e.Tag == dwarf.TagSubprogram {
- min := core.Address(e.AttrField(dwarf.AttrLowpc).Val.(uint64))
- max := core.Address(e.AttrField(dwarf.AttrHighpc).Val.(uint64))
+ lowpc := e.AttrField(dwarf.AttrLowpc)
+ highpc := e.AttrField(dwarf.AttrHighpc)
+ if lowpc == nil || highpc == nil {
+ continue
+ }
+ min := core.Address(lowpc.Val.(uint64))
+ max := core.Address(highpc.Val.(uint64))
f := p.funcTab.find(min)
if f == nil {
// some func Go doesn't know about. C?
@@ -477,11 +498,19 @@
if len(loc) != 0 {
continue // more stuff we don't recognize
}
- dt, err := d.Type(e.AttrField(dwarf.AttrType).Val.(dwarf.Offset))
+ f := e.AttrField(dwarf.AttrType)
+ if f == nil {
+ continue
+ }
+ dt, err := d.Type(f.Val.(dwarf.Offset))
if err != nil {
panic(err)
}
- name := e.AttrField(dwarf.AttrName).Val.(string)
+ nf := e.AttrField(dwarf.AttrName)
+ if nf == nil {
+ continue
+ }
+ name := nf.Val.(string)
vars[curfn] = append(vars[curfn], Var{name: name, off: off, typ: p.dwarfMap[dt]})
}
