1 files changed, 34 insertions, 18 deletions

diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index cc29869d12a3..bf85d6db4931 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -929,7 +929,11 @@ static inline void emit_a32_rsh_i64(const s8 dst[],
 	rd = arm_bpf_get_reg64(dst, tmp, ctx);
 
 	/* Do LSR operation */
-	if (val < 32) {
+	if (val == 0) {
+		/* An immediate value of 0 encodes a shift amount of 32
+		 * for LSR. To shift by 0, don't do anything.
+		 */
+	} else if (val < 32) {
 		emit(ARM_MOV_SI(tmp2[1], rd[1], SRTYPE_LSR, val), ctx);
 		emit(ARM_ORR_SI(rd[1], tmp2[1], rd[0], SRTYPE_ASL, 32 - val), ctx);
 		emit(ARM_MOV_SI(rd[0], rd[0], SRTYPE_LSR, val), ctx);
@@ -955,7 +959,11 @@ static inline void emit_a32_arsh_i64(const s8 dst[],
 	rd = arm_bpf_get_reg64(dst, tmp, ctx);
 
 	/* Do ARSH operation */
-	if (val < 32) {
+	if (val == 0) {
+		/* An immediate value of 0 encodes a shift amount of 32
+		 * for ASR. To shift by 0, don't do anything.
+		 */
+	} else if (val < 32) {
 		emit(ARM_MOV_SI(tmp2[1], rd[1], SRTYPE_LSR, val), ctx);
 		emit(ARM_ORR_SI(rd[1], tmp2[1], rd[0], SRTYPE_ASL, 32 - val), ctx);
 		emit(ARM_MOV_SI(rd[0], rd[0], SRTYPE_ASR, val), ctx);
@@ -992,21 +1000,35 @@ static inline void emit_a32_mul_r64(const s8 dst[], const s8 src[],
 	arm_bpf_put_reg32(dst_hi, rd[0], ctx);
 }
 
+static bool is_ldst_imm(s16 off, const u8 size)
+{
+	s16 off_max = 0;
+
+	switch (size) {
+	case BPF_B:
+	case BPF_W:
+		off_max = 0xfff;
+		break;
+	case BPF_H:
+		off_max = 0xff;
+		break;
+	case BPF_DW:
+		/* Need to make sure off+4 does not overflow. */
+		off_max = 0xfff - 4;
+		break;
+	}
+	return -off_max <= off && off <= off_max;
+}
+
 /* *(size *)(dst + off) = src */
 static inline void emit_str_r(const s8 dst, const s8 src[],
-			      s32 off, struct jit_ctx *ctx, const u8 sz){
+			      s16 off, struct jit_ctx *ctx, const u8 sz){
 	const s8 *tmp = bpf2a32[TMP_REG_1];
-	s32 off_max;
 	s8 rd;
 
 	rd = arm_bpf_get_reg32(dst, tmp[1], ctx);
 
-	if (sz == BPF_H)
-		off_max = 0xff;
-	else
-		off_max = 0xfff;
-
-	if (off < 0 || off > off_max) {
+	if (!is_ldst_imm(off, sz)) {
 		emit_a32_mov_i(tmp[0], off, ctx);
 		emit(ARM_ADD_R(tmp[0], tmp[0], rd), ctx);
 		rd = tmp[0];
@@ -1035,18 +1057,12 @@ static inline void emit_str_r(const s8 dst, const s8 src[],
 
 /* dst = *(size*)(src + off) */
 static inline void emit_ldx_r(const s8 dst[], const s8 src,
-			      s32 off, struct jit_ctx *ctx, const u8 sz){
+			      s16 off, struct jit_ctx *ctx, const u8 sz){
 	const s8 *tmp = bpf2a32[TMP_REG_1];
 	const s8 *rd = is_stacked(dst_lo) ? tmp : dst;
 	s8 rm = src;
-	s32 off_max;
-
-	if (sz == BPF_H)
-		off_max = 0xff;
-	else
-		off_max = 0xfff;
 
-	if (off < 0 || off > off_max) {
+	if (!is_ldst_imm(off, sz)) {
 		emit_a32_mov_i(tmp[0], off, ctx);
 		emit(ARM_ADD_R(tmp[0], tmp[0], src), ctx);
 		rm = tmp[0];