diff --git a/cffdump/crashdec.c b/cffdump/crashdec.c
index 1fef6871..a50b17f4 100644
--- a/cffdump/crashdec.c
+++ b/cffdump/crashdec.c
@@ -40,6 +40,7 @@
 #include <assert.h>
 #include <getopt.h>
 #include <inttypes.h>
+#include <setjmp.h>
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdint.h>
@@ -208,6 +209,34 @@ parseline(const char *line, const char *fmt, ...)
 			break;                                                \
 		} else
 
+/*
+ * Provide our own disasm assert() handler, so that we can recover
+ * after attempting to disassemble things that might not be valid
+ * instructions:
+ */
+
+static bool jmp_env_valid;
+static jmp_buf jmp_env;
+
+void
+ir3_assert_handler(const char *expr, const char *file, int line,
+		const char *func)
+{
+	printf("%s:%u: %s: Assertion `%s' failed.\n", file, line, func, expr);
+	if (jmp_env_valid)
+		longjmp(jmp_env, 1);
+	abort();
+}
+
+#define TRY(x) do { \
+		assert(!jmp_env_valid); \
+		if (setjmp(jmp_env) == 0) { \
+			jmp_env_valid = true; \
+			x; \
+		} \
+		jmp_env_valid = false; \
+	} while (0)
+
 /*
  * Decode ringbuffer section:
  */
@@ -299,6 +328,8 @@ dump_cmdstream(void)
 	for (int id = 0; id < ARRAY_SIZE(ringbuffers); id++) {
 		if (ringbuffers[id].iova != rb_base)
 			continue;
+		if (!ringbuffers[id].size)
+			continue;
 
 		printf("found ring!\n");
 
@@ -877,7 +908,7 @@ decode_shader_blocks(void)
 				 * (or parts of shaders?), so perhaps we should search
 				 * for ends of shaders and decode each?
 				 */
-				disasm_a3xx(buf, sizedwords, 1, stdout, options.gpu_id);
+				TRY(disasm_a3xx(buf, sizedwords, 1, stdout, options.gpu_id));
 			}
 
 			if (dump)
diff --git a/cffdump/disasm-a3xx.c b/cffdump/disasm-a3xx.c
index 249563bb..9645dc5f 100644
--- a/cffdump/disasm-a3xx.c
+++ b/cffdump/disasm-a3xx.c
@@ -174,7 +174,7 @@ static void regmask_set(regmask_t *regmask, unsigned num, bool full, unsigned va
 {
 	unsigned i = num / 8;
 	unsigned j = num % 8;
-	assert(num < MAX_REG);
+	ir3_assert(num < MAX_REG);
 	if (full) {
 		regmask->full[i] = (regmask->full[i] & ~(1 << j)) | (val << j);
 	} else {
@@ -186,7 +186,7 @@ static unsigned regmask_get(regmask_t *regmask, unsigned num, bool full)
 {
 	unsigned i = num / 8;
 	unsigned j = num % 8;
-	assert(num < MAX_REG);
+	ir3_assert(num < MAX_REG);
 	if (full) {
 		return (regmask->full[i] >> j) & 0x1;
 	} else {
@@ -1614,7 +1614,7 @@ int disasm_a3xx_stat(uint32_t *dwords, int sizedwords, int level, FILE *out,
 	int nop_count = 0;
 	bool has_end = false;
 
-//	assert((sizedwords % 2) == 0);
+//	ir3_assert((sizedwords % 2) == 0);
 
 	memset(&ctx, 0, sizeof(ctx));
 	ctx.out = out;
diff --git a/cffdump/instr-a3xx.h b/cffdump/instr-a3xx.h
index b372bd14..218bdc3e 100644
--- a/cffdump/instr-a3xx.h
+++ b/cffdump/instr-a3xx.h
@@ -30,6 +30,23 @@
 #include <stdbool.h>
 #include <assert.h>
 
+void ir3_assert_handler(const char *expr, const char *file, int line,
+		const char *func) __attribute__((weak)) __attribute__ ((__noreturn__));
+
+/* A wrapper for assert() that allows overriding handling of a failed
+ * assert.  This is needed for tools like crashdec which can want to
+ * attempt to disassemble memory that might not actually be valid
+ * instructions.
+ */
+#define ir3_assert(expr) do { \
+		if (!(expr)) { \
+			if (ir3_assert_handler) { \
+				ir3_assert_handler(#expr, __FILE__, __LINE__, __func__); \
+			} \
+			assert(expr); \
+		} \
+	} while (0)
+
 /* size of largest OPC field of all the instruction categories: */
 #define NOPC_BITS 6
 
@@ -251,7 +268,7 @@ static inline uint32_t type_size(type_t type)
 	case TYPE_S8:
 		return 8;
 	default:
-		assert(0); /* invalid type */
+		ir3_assert(0); /* invalid type */
 		return 0;
 	}
 }
@@ -958,8 +975,8 @@ static inline bool is_cat6_legacy(instr_t *instr, unsigned gpu_id)
 	 * in all cases.  So we can use this to detect new encoding:
 	 */
 	if ((cat6->pad3 & 0x8) && (cat6->pad5 & 0x2)) {
-		assert(gpu_id >= 600);
-		assert(instr->cat6.opc == 0);
+		ir3_assert(gpu_id >= 600);
+		ir3_assert(instr->cat6.opc == 0);
 		return false;
 	}