diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
index ab76b36dce82..73cce8ac8368 100644
--- a/arch/arm64/kernel/hw_breakpoint.c
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -559,6 +559,15 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 		else
 			alignment_mask = 0x7;
 		offset = hw->address & alignment_mask;
+
+		/*
+		 * BAS is an 8-bit field in WCR/BCR; the shift below would
+		 * silently drop the high bits of ctrl.len when offset + len
+		 * exceeds 8, programming hardware to watch fewer bytes than
+		 * the user requested.
+		 */
+		if (((u32)hw->ctrl.len << offset) > ARM_BREAKPOINT_LEN_8)
+			return -EINVAL;
 	}
 
 	hw->address &= ~alignment_mask;