cmd/internal/obj/wasm: avoid invalid offsets for Load/Store

Offsets for Load and Store instructions have type i32. Bad index
expression offsets can cause an offset to be larger than MaxUint32,
which is not allowed. One example for this is the test test/index0.go.

Generate valid code by adding a guard to the responsible rewrite rule.
Also emit a proper error when using such a bad index in assembly code.

Change-Id: Ie90adcbf3ae3861c26680eb81790f28692913ccf
Reviewed-on: https://go-review.googlesource.com/111955
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

3 files changed, 34 insertions, 33 deletions

diff --git a/src/cmd/compile/internal/ssa/gen/Wasm.rules b/src/cmd/compile/internal/ssa/gen/Wasm.rules
index cede359c53..7994fb7f5b 100644
--- a/src/cmd/compile/internal/ssa/gen/Wasm.rules
+++ b/src/cmd/compile/internal/ssa/gen/Wasm.rules
@@ -377,15 +377,10 @@
 (I64Add x (I64Const [y])) -> (I64AddConst [y] x)
 (I64Eqz (I64Eqz (I64Eqz x))) -> (I64Eqz x)
 
-(I64Store8 [off] (I64AddConst [off2] ptr) val mem) && off+off2 >= 0 -> (I64Store8 [off+off2] ptr val mem)
-(I64Store16 [off] (I64AddConst [off2] ptr) val mem) && off+off2 >= 0 -> (I64Store16 [off+off2] ptr val mem)
-(I64Store32 [off] (I64AddConst [off2] ptr) val mem) && off+off2 >= 0 -> (I64Store32 [off+off2] ptr val mem)
-(I64Store [off] (I64AddConst [off2] ptr) val mem) && off+off2 >= 0 -> (I64Store [off+off2] ptr val mem)
+((I64Load|I64Load32U|I64Load32S|I64Load16U|I64Load16S|I64Load8U|I64Load8S) [off] (I64AddConst [off2] ptr) mem)
+	&& isU32Bit(off+off2) ->
+	((I64Load|I64Load32U|I64Load32S|I64Load16U|I64Load16S|I64Load8U|I64Load8S) [off+off2] ptr mem)
 
-(I64Load8U [off] (I64AddConst [off2] ptr) mem) && off+off2 >= 0 -> (I64Load8U [off+off2] ptr mem)
-(I64Load8S [off] (I64AddConst [off2] ptr) mem) && off+off2 >= 0 -> (I64Load8S [off+off2] ptr mem)
-(I64Load16U [off] (I64AddConst [off2] ptr) mem) && off+off2 >= 0 -> (I64Load16U [off+off2] ptr mem)
-(I64Load16S [off] (I64AddConst [off2] ptr) mem) && off+off2 >= 0 -> (I64Load16S [off+off2] ptr mem)
-(I64Load32U [off] (I64AddConst [off2] ptr) mem) && off+off2 >= 0 -> (I64Load32U [off+off2] ptr mem)
-(I64Load32S [off] (I64AddConst [off2] ptr) mem) && off+off2 >= 0 -> (I64Load32S [off+off2] ptr mem)
-(I64Load [off] (I64AddConst [off2] ptr) mem) && off+off2 >= 0 -> (I64Load [off+off2] ptr mem)
+((I64Store|I64Store32|I64Store16|I64Store8) [off] (I64AddConst [off2] ptr) val mem)
+	&& isU32Bit(off+off2) ->
+	((I64Store|I64Store32|I64Store16|I64Store8) [off+off2] ptr val mem)
diff --git a/src/cmd/compile/internal/ssa/rewriteWasm.go b/src/cmd/compile/internal/ssa/rewriteWasm.go
index f488a93522..2255561051 100644
--- a/src/cmd/compile/internal/ssa/rewriteWasm.go
+++ b/src/cmd/compile/internal/ssa/rewriteWasm.go
@@ -5256,7 +5256,7 @@ func rewriteValueWasm_OpWasmI64Eqz_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Load_0(v *Value) bool {
 	// match: (I64Load [off] (I64AddConst [off2] ptr) mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Load [off+off2] ptr mem)
 	for {
 		off := v.AuxInt
@@ -5268,7 +5268,7 @@ func rewriteValueWasm_OpWasmI64Load_0(v *Value) bool {
 		off2 := v_0.AuxInt
 		ptr := v_0.Args[0]
 		mem := v.Args[1]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Load)
@@ -5281,7 +5281,7 @@ func rewriteValueWasm_OpWasmI64Load_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Load16S_0(v *Value) bool {
 	// match: (I64Load16S [off] (I64AddConst [off2] ptr) mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Load16S [off+off2] ptr mem)
 	for {
 		off := v.AuxInt
@@ -5293,7 +5293,7 @@ func rewriteValueWasm_OpWasmI64Load16S_0(v *Value) bool {
 		off2 := v_0.AuxInt
 		ptr := v_0.Args[0]
 		mem := v.Args[1]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Load16S)
@@ -5306,7 +5306,7 @@ func rewriteValueWasm_OpWasmI64Load16S_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Load16U_0(v *Value) bool {
 	// match: (I64Load16U [off] (I64AddConst [off2] ptr) mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Load16U [off+off2] ptr mem)
 	for {
 		off := v.AuxInt
@@ -5318,7 +5318,7 @@ func rewriteValueWasm_OpWasmI64Load16U_0(v *Value) bool {
 		off2 := v_0.AuxInt
 		ptr := v_0.Args[0]
 		mem := v.Args[1]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Load16U)
@@ -5331,7 +5331,7 @@ func rewriteValueWasm_OpWasmI64Load16U_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Load32S_0(v *Value) bool {
 	// match: (I64Load32S [off] (I64AddConst [off2] ptr) mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Load32S [off+off2] ptr mem)
 	for {
 		off := v.AuxInt
@@ -5343,7 +5343,7 @@ func rewriteValueWasm_OpWasmI64Load32S_0(v *Value) bool {
 		off2 := v_0.AuxInt
 		ptr := v_0.Args[0]
 		mem := v.Args[1]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Load32S)
@@ -5356,7 +5356,7 @@ func rewriteValueWasm_OpWasmI64Load32S_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Load32U_0(v *Value) bool {
 	// match: (I64Load32U [off] (I64AddConst [off2] ptr) mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Load32U [off+off2] ptr mem)
 	for {
 		off := v.AuxInt
@@ -5368,7 +5368,7 @@ func rewriteValueWasm_OpWasmI64Load32U_0(v *Value) bool {
 		off2 := v_0.AuxInt
 		ptr := v_0.Args[0]
 		mem := v.Args[1]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Load32U)
@@ -5381,7 +5381,7 @@ func rewriteValueWasm_OpWasmI64Load32U_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Load8S_0(v *Value) bool {
 	// match: (I64Load8S [off] (I64AddConst [off2] ptr) mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Load8S [off+off2] ptr mem)
 	for {
 		off := v.AuxInt
@@ -5393,7 +5393,7 @@ func rewriteValueWasm_OpWasmI64Load8S_0(v *Value) bool {
 		off2 := v_0.AuxInt
 		ptr := v_0.Args[0]
 		mem := v.Args[1]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Load8S)
@@ -5406,7 +5406,7 @@ func rewriteValueWasm_OpWasmI64Load8S_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Load8U_0(v *Value) bool {
 	// match: (I64Load8U [off] (I64AddConst [off2] ptr) mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Load8U [off+off2] ptr mem)
 	for {
 		off := v.AuxInt
@@ -5418,7 +5418,7 @@ func rewriteValueWasm_OpWasmI64Load8U_0(v *Value) bool {
 		off2 := v_0.AuxInt
 		ptr := v_0.Args[0]
 		mem := v.Args[1]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Load8U)
@@ -5588,7 +5588,7 @@ func rewriteValueWasm_OpWasmI64Or_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Store_0(v *Value) bool {
 	// match: (I64Store [off] (I64AddConst [off2] ptr) val mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Store [off+off2] ptr val mem)
 	for {
 		off := v.AuxInt
@@ -5601,7 +5601,7 @@ func rewriteValueWasm_OpWasmI64Store_0(v *Value) bool {
 		ptr := v_0.Args[0]
 		val := v.Args[1]
 		mem := v.Args[2]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Store)
@@ -5615,7 +5615,7 @@ func rewriteValueWasm_OpWasmI64Store_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Store16_0(v *Value) bool {
 	// match: (I64Store16 [off] (I64AddConst [off2] ptr) val mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Store16 [off+off2] ptr val mem)
 	for {
 		off := v.AuxInt
@@ -5628,7 +5628,7 @@ func rewriteValueWasm_OpWasmI64Store16_0(v *Value) bool {
 		ptr := v_0.Args[0]
 		val := v.Args[1]
 		mem := v.Args[2]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Store16)
@@ -5642,7 +5642,7 @@ func rewriteValueWasm_OpWasmI64Store16_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Store32_0(v *Value) bool {
 	// match: (I64Store32 [off] (I64AddConst [off2] ptr) val mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Store32 [off+off2] ptr val mem)
 	for {
 		off := v.AuxInt
@@ -5655,7 +5655,7 @@ func rewriteValueWasm_OpWasmI64Store32_0(v *Value) bool {
 		ptr := v_0.Args[0]
 		val := v.Args[1]
 		mem := v.Args[2]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Store32)
@@ -5669,7 +5669,7 @@ func rewriteValueWasm_OpWasmI64Store32_0(v *Value) bool {
 }
 func rewriteValueWasm_OpWasmI64Store8_0(v *Value) bool {
 	// match: (I64Store8 [off] (I64AddConst [off2] ptr) val mem)
-	// cond: off+off2 >= 0
+	// cond: isU32Bit(off+off2)
 	// result: (I64Store8 [off+off2] ptr val mem)
 	for {
 		off := v.AuxInt
@@ -5682,7 +5682,7 @@ func rewriteValueWasm_OpWasmI64Store8_0(v *Value) bool {
 		ptr := v_0.Args[0]
 		val := v.Args[1]
 		mem := v.Args[2]
-		if !(off+off2 >= 0) {
+		if !(isU32Bit(off + off2)) {
 			break
 		}
 		v.reset(OpWasmI64Store8)
diff --git a/src/cmd/internal/obj/wasm/wasmobj.go b/src/cmd/internal/obj/wasm/wasmobj.go
index 2b7e12a93f..ca09b3fa0b 100644
--- a/src/cmd/internal/obj/wasm/wasmobj.go
+++ b/src/cmd/internal/obj/wasm/wasmobj.go
@@ -870,6 +870,9 @@ func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
 			if p.From.Type != obj.TYPE_CONST {
 				panic("bad type for *Load")
 			}
+			if p.From.Offset > math.MaxUint32 {
+				ctxt.Diag("bad offset in %v", p)
+			}
 			writeUleb128(w, align(p.As))
 			writeUleb128(w, uint64(p.From.Offset))
 
@@ -877,6 +880,9 @@ func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
 			if p.To.Offset < 0 {
 				panic("negative offset")
 			}
+			if p.From.Offset > math.MaxUint32 {
+				ctxt.Diag("bad offset in %v", p)
+			}
 			writeUleb128(w, align(p.As))
 			writeUleb128(w, uint64(p.To.Offset))