fix: prevent infinite loop in cfIEEE1284NormalizeMakeModel on empty MFG/MDL (fixes #214)

Makefile.am

@@ -106,6 +106,7 @@ check_PROGRAMS = \
 	test-analyze \
 	test-pdf \
 	test-ps \
+	test-ieee1284-normalize \
 	testfilters
 
 TESTS = \
@@ -115,6 +116,7 @@ TESTS = \
 	test-analyze \
 	test-pdf \
 	test-ps \
+	test-ieee1284-normalize \
 	cupsfilters/testfilters.sh \
 	cupsfilters/test-pclm-overflow.sh \
 	cupsfilters/test-pdftoraster-copy-height.sh
@@ -289,6 +291,15 @@ test1284_CFLAGS = \
 	-I$(srcdir)/cupsfilters/ \
 	$(CUPS_CFLAGS)
 
+test_ieee1284_normalize_SOURCES = \
+	cupsfilters/test-ieee1284-normalize.c
+test_ieee1284_normalize_CFLAGS = \
+	-I$(srcdir)/cupsfilters/ \
+	$(CUPS_CFLAGS)
+test_ieee1284_normalize_LDADD = \
+	libcupsfilters.la \
+	$(CUPS_LIBS)
+
 testpdf1_SOURCES = \
 	cupsfilters/testpdf1.c \
 	cupsfilters/fontembed-private.h

cupsfilters/ieee1284.c

@@ -804,8 +804,8 @@ cfIEEE1284NormalizeMakeModel(
       makeptr ++;
       bufptr ++;
     }
-    while (isspace(*(bufptr - 1))) bufptr --;
-    if (bufptr < buffer + bufsize - 1)
+    while (bufptr > buffer && isspace(*(bufptr - 1))) bufptr --;
+    if (bufptr > buffer && bufptr < buffer + bufsize - 1)
     {
       *bufptr = ' ';
       makeptr ++;
@@ -822,7 +822,7 @@ cfIEEE1284NormalizeMakeModel(
       modelptr ++;
       bufptr ++;
     }
-    while (isspace(*(bufptr - 1))) bufptr --;
+    while (bufptr > buffer && isspace(*(bufptr - 1))) bufptr --;
     *bufptr = '\0';
     if (!nomakemodel && makeptr != bufptr)
       modelptr = makeptr;
@@ -1161,6 +1161,9 @@ cfIEEE1284NormalizeMakeModel(
     // Remove repeated manufacturer names...
     //
 
+    if (!modelptr || modelptr > buffer + strlen(buffer))
+      modelptr = buffer + strlen(buffer);
+
     compare_len = modelptr - buffer;
     while (compare_len > 0 && strncasecmp(buffer, modelptr, compare_len) == 0)
       move_right_part(buffer, bufsize, modelptr, buffer - modelptr);

cupsfilters/test-ieee1284-normalize.c

@@ -0,0 +1,73 @@
+//
+// IEEE-1284 normalization regression test for libcupsfilters (Issue #214).
+//
+// Copyright © 2026 by OpenPrinting.
+//
+// Licensed under Apache License v2.0. See the file "LICENSE" for more
+// information.
+//
+
+#include <config.h>
+#include <cupsfilters/ieee1284.h>
+#include <stdio.h>
+#include <string.h>
+
+int
+main(void)
+{
+  char	buffer[1024];	// Make/model buffer
+  char	*model = NULL;	// Pointer to model name
+  char	*res;		// Result pointer
+
+  //
+  // Issue #214 regression test: empty MFG and MDL fields in IEEE-1284 device ID
+  //
+
+  res = cfIEEE1284NormalizeMakeModel("MFG:;MDL:;", NULL,
+				     CF_IEEE1284_NORMALIZE_HUMAN, NULL,
+				     buffer, sizeof(buffer), &model, NULL,
+				     NULL);
+  if (res != NULL)
+  {
+    printf("FAIL: MFG:;MDL:; expected NULL, got \"%s\"\n", res);
+    return (1);
+  }
+
+  res = cfIEEE1284NormalizeMakeModel("MFG:;MDL:;CMD:PostScript;", NULL,
+				     CF_IEEE1284_NORMALIZE_HUMAN, NULL,
+				     buffer, sizeof(buffer), &model, NULL,
+				     NULL);
+  if (res != NULL)
+  {
+    printf("FAIL: MFG:;MDL:;CMD:PostScript; expected NULL, got \"%s\"\n", res);
+    return (1);
+  }
+
+  //
+  // Verify valid inputs behavior preservation
+  //
+
+  res = cfIEEE1284NormalizeMakeModel("MDL:;", NULL,
+				     CF_IEEE1284_NORMALIZE_HUMAN, NULL,
+				     buffer, sizeof(buffer), &model, NULL,
+				     NULL);
+  if (!res || strcmp(res, "MDL:;"))
+  {
+    printf("FAIL: MDL:; expected \"MDL:;\", got \"%s\"\n", res ? res : "NULL");
+    return (1);
+  }
+
+  res = cfIEEE1284NormalizeMakeModel("MFG:HP;MDL:DeskJet;", NULL,
+				     CF_IEEE1284_NORMALIZE_HUMAN, NULL,
+				     buffer, sizeof(buffer), &model, NULL,
+				     NULL);
+  if (!res || strcmp(res, "HP DeskJet"))
+  {
+    printf("FAIL: MFG:HP;MDL:DeskJet; expected \"HP DeskJet\", got \"%s\"\n",
+	   res ? res : "NULL");
+    return (1);
+  }
+
+  puts("PASS: cfIEEE1284NormalizeMakeModel issue #214 tests passed.");
+  return (0);
+}