asm: more early returns on errors
More protection against random input bytes.
Fixes #12614.
Change-Id: Ie9f817de1376a10bb80b22ecee3bae4f1d26cc6c
Reviewed-on: https://go-review.googlesource.com/14563
Reviewed-by: Andrew Gerrand <adg@golang.org>
diff --git a/src/cmd/asm/internal/asm/asm.go b/src/cmd/asm/internal/asm/asm.go
index 4c63b51..6128ca8 100644
--- a/src/cmd/asm/internal/asm/asm.go
+++ b/src/cmd/asm/internal/asm/asm.go
@@ -67,13 +67,17 @@
}
}
-// validateSymbol checks that addr represents a valid name for a pseudo-op.
-func (p *Parser) validateSymbol(pseudo string, addr *obj.Addr, offsetOk bool) {
+// validSymbol checks that addr represents a valid name for a pseudo-op.
+func (p *Parser) validSymbol(pseudo string, addr *obj.Addr, offsetOk bool) bool {
if addr.Name != obj.NAME_EXTERN && addr.Name != obj.NAME_STATIC || addr.Scale != 0 || addr.Reg != 0 {
p.errorf("%s symbol %q must be a symbol(SB)", pseudo, symbolName(addr))
- } else if !offsetOk && addr.Offset != 0 {
- p.errorf("%s symbol %q must not be offset from SB", pseudo, symbolName(addr))
+ return false
}
+ if !offsetOk && addr.Offset != 0 {
+ p.errorf("%s symbol %q must not be offset from SB", pseudo, symbolName(addr))
+ return false
+ }
+ return true
}
// evalInteger evaluates an integer constant for a pseudo-op.
@@ -82,11 +86,13 @@
return p.getConstantPseudo(pseudo, &addr)
}
-// validateImmediate checks that addr represents an immediate constant.
-func (p *Parser) validateImmediate(pseudo string, addr *obj.Addr) {
+// validImmediate checks that addr represents an immediate constant.
+func (p *Parser) validImmediate(pseudo string, addr *obj.Addr) bool {
if addr.Type != obj.TYPE_CONST || addr.Name != 0 || addr.Reg != 0 || addr.Index != 0 {
p.errorf("%s: expected immediate constant; found %s", pseudo, obj.Dconv(&emptyProg, addr))
+ return false
}
+ return true
}
// asmText assembles a TEXT pseudo-op.
@@ -105,7 +111,9 @@
// Operand 0 is the symbol name in the form foo(SB).
// That means symbol plus indirect on SB and no offset.
nameAddr := p.address(operands[0])
- p.validateSymbol("TEXT", &nameAddr, false)
+ if !p.validSymbol("TEXT", &nameAddr, false) {
+ return
+ }
name := symbolName(&nameAddr)
next := 1
@@ -189,7 +197,9 @@
scale := p.parseScale(op[n-1].String())
op = op[:n-2]
nameAddr := p.address(op)
- p.validateSymbol("DATA", &nameAddr, true)
+ if !p.validSymbol("DATA", &nameAddr, true) {
+ return
+ }
name := symbolName(&nameAddr)
// Operand 1 is an immediate constant or address.
@@ -234,7 +244,9 @@
// Operand 0 has the general form foo<>+0x04(SB).
nameAddr := p.address(operands[0])
- p.validateSymbol("GLOBL", &nameAddr, false)
+ if !p.validSymbol("GLOBL", &nameAddr, false) {
+ return
+ }
next := 1
// Next operand is the optional flag, a literal integer.
@@ -246,7 +258,9 @@
// Final operand is an immediate constant.
addr := p.address(operands[next])
- p.validateImmediate("GLOBL", &addr)
+ if !p.validImmediate("GLOBL", &addr) {
+ return
+ }
// log.Printf("GLOBL %s %d, $%d", name, flag, size)
prog := &obj.Prog{
@@ -272,11 +286,15 @@
// Operand 0 must be an immediate constant.
key := p.address(operands[0])
- p.validateImmediate("PCDATA", &key)
+ if !p.validImmediate("PCDATA", &key) {
+ return
+ }
// Operand 1 must be an immediate constant.
value := p.address(operands[1])
- p.validateImmediate("PCDATA", &value)
+ if !p.validImmediate("PCDATA", &value) {
+ return
+ }
// log.Printf("PCDATA $%d, $%d", key.Offset, value.Offset)
prog := &obj.Prog{
@@ -299,11 +317,15 @@
// Operand 0 must be an immediate constant.
valueAddr := p.address(operands[0])
- p.validateImmediate("FUNCDATA", &valueAddr)
+ if !p.validImmediate("FUNCDATA", &valueAddr) {
+ return
+ }
// Operand 1 is a symbol name in the form foo(SB).
nameAddr := p.address(operands[1])
- p.validateSymbol("FUNCDATA", &nameAddr, true)
+ if !p.validSymbol("FUNCDATA", &nameAddr, true) {
+ return
+ }
prog := &obj.Prog{
Ctxt: p.ctxt,
