arm unwind: Reject unaligned stack pointers

Reviewed by:	andrew
Differential Revision:	https://reviews.freebsd.org/D41533

sys/arm/arm/unwind.c

@@ -398,6 +398,9 @@ unwind_exec_insn(struct unwind_state *state)
 		if (mask == 0)
 			return 1;
 
+		if (!__is_aligned(vsp, sizeof(register_t)))
+			return 1;
+
 		/* Update SP */
 		update_vsp = 1;
 
@@ -430,6 +433,9 @@ unwind_exec_insn(struct unwind_state *state)
 		/* Read how many registers to load */
 		count = insn & INSN_POP_COUNT_MASK;
 
+		if (!__is_aligned(vsp, sizeof(register_t)))
+			return 1;
+
 		/* Update sp */
 		update_vsp = 1;
 
@@ -460,6 +466,9 @@ unwind_exec_insn(struct unwind_state *state)
 		if (mask == 0 || (mask & 0xf0) != 0)
 			return 1;
 
+		if (!__is_aligned(vsp, sizeof(register_t)))
+			return 1;
+
 		/* Update SP */
 		update_vsp = 1;