--- libclamunrar/unrarvm.c.orig
+++ libclamunrar/unrarvm.c
@@ -26,6 +26,13 @@
 #include "libclamunrar/unrarvm.h"
 #include "libclamunrar/unrarcmd.h"
 
+/*
+ * Limit maximum number of channels in RAR3 delta filter to some
+ * reasonable value to prevent too slow processing of corrupt archives
+ * with invalid channels number.
+ */
+#define MAX3_UNPACK_CHANNELS 1024
+
 #ifdef RAR_HIGH_DEBUG
 #define rar_dbgmsg printf
 #else
@@ -340,8 +347,8 @@ static void filter_itanium_setbits(unsig
 static void execute_standard_filter(rarvm_data_t *rarvm_data, rarvm_standard_filters_t filter_type)
 {
 	unsigned char *data, cmp_byte2, cur_byte, *src_data, *dest_data;
-	int i, j, data_size, channels, src_pos, dest_pos, border, width, PosR;
-	int op_type, cur_channel, byte_count, start_pos, pa, pb, pc;
+	int i, j, op_type, cur_channel, byte_count, start_pos, pa, pb, pc;
+	unsigned int data_size, channels, src_pos, dest_pos, border, width, PosR;
 	unsigned int file_offset, cur_pos, predicted;
 	int32_t offset, addr;
 	const int file_size=0x1000000;
@@ -426,7 +433,7 @@ static void execute_standard_filter(rarv
 		border = data_size*2;
 		
 		SET_VALUE(FALSE, &rarvm_data->mem[VM_GLOBALMEMADDR+0x20], data_size);
-		if ((unsigned int)data_size >= VM_GLOBALMEMADDR/2) {
+		if ((unsigned int)data_size >= VM_GLOBALMEMADDR/2 || channels > MAX3_UNPACK_CHANNELS) {
 			break;
 		}
 		for (cur_channel=0 ; cur_channel < channels ; cur_channel++) {