@@ -, +, @@ 
---
 lib/util/charset/util_str.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)
--- a/lib/util/charset/util_str.c	
+++ a/lib/util/charset/util_str.c	
@@ -56,7 +56,17 @@ _PUBLIC_ int strcasecmp_m_handle(struct smb_iconv_handle *iconv_handle,
 
 		if (c1 == INVALID_CODEPOINT ||
 		    c2 == INVALID_CODEPOINT) {
-			/* what else can we do?? */
+			/*
+			 * Fall back to byte
+			 * comparison. We must
+			 * step back by the codepoint
+			 * length we just incremented
+			 * - otherwise we are not
+			 * checking the bytes that
+			 * failed the conversion.
+			 */
+			s1 -= size1;
+			s2 -= size2;
 			return strcasecmp(s1, s2);
 		}
 
-- 
---
 lib/util/charset/util_str.c |   29 +++++++++++++++++++++++++++--
 1 files changed, 27 insertions(+), 2 deletions(-)
--- a/lib/util/charset/util_str.c	
+++ a/lib/util/charset/util_str.c	
@@ -116,8 +116,33 @@ _PUBLIC_ int strncasecmp_m_handle(struct smb_iconv_handle *iconv_handle,
 
 		if (c1 == INVALID_CODEPOINT ||
 		    c2 == INVALID_CODEPOINT) {
-			/* what else can we do?? */
-			return strcasecmp(s1, s2);
+			/*
+			 * Fall back to byte
+			 * comparison. We must
+			 * step back by the codepoint
+			 * length we just incremented
+			 * by - otherwise we are not
+			 * checking the bytes that
+			 * failed the conversion.
+			 */
+			s1 -= size1;
+			s2 -= size2;
+			/*
+			 * n was specified in characters,
+			 * now we must convert it to bytes.
+			 * As bytes are the smallest
+			 * character unit, the following
+			 * increment and strncasecmp is always
+			 * safe.
+			 *
+			 * The source string was already known
+			 * to be n characters long, so we are
+			 * guaranteed to be able to look at the
+			 * (n remaining + size1) bytes from the
+			 * new (s1 - size1) position).
+			 */
+			n += size1;
+			return strncasecmp(s1, s2, n);
 		}
 
 		if (toupper_m(c1) != toupper_m(c2)) {
-- 
---
 lib/util/charset/tests/charset.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
--- a/lib/util/charset/tests/charset.c	
+++ a/lib/util/charset/tests/charset.c	
@@ -50,12 +50,18 @@ static bool test_codepoint_cmpi(struct torture_context *tctx)
 
 static bool test_strcasecmp_m(struct torture_context *tctx)
 {
+	/* file.{accented e} in iso8859-1 */
+	const char file_iso8859_1[7] = { 0x66, 0x69, 0x6c, 0x65, 0x2d, 0xe9, 0 };
+	/* file.{accented e} in utf8 */
+	const char file_utf8[8] =      { 0x66, 0x69, 0x6c, 0x65, 0x2d, 0xc3, 0xa9, 0 };
 	torture_assert(tctx, strcasecmp_m("foo", "bar") != 0, "different strings");
 	torture_assert(tctx, strcasecmp_m("foo", "foo") == 0, "same case strings");
 	torture_assert(tctx, strcasecmp_m("foo", "Foo") == 0, "different case strings");
 	torture_assert(tctx, strcasecmp_m(NULL, "Foo") != 0, "one NULL");
 	torture_assert(tctx, strcasecmp_m("foo", NULL) != 0, "other NULL");
 	torture_assert(tctx, strcasecmp_m(NULL, NULL) == 0, "both NULL");
+	torture_assert(tctx, strcasecmp_m(file_iso8859_1, file_utf8) != 0,
+		"file.{accented e} should differ");
 	return true;
 }
 
@@ -102,6 +108,10 @@ static bool test_string_replace_m(struct torture_context *tctx)
 
 static bool test_strncasecmp_m(struct torture_context *tctx)
 {
+	/* file.{accented e} in iso8859-1 */
+	const char file_iso8859_1[7] = { 0x66, 0x69, 0x6c, 0x65, 0x2d, 0xe9, 0 };
+	/* file.{accented e} in utf8 */
+	const char file_utf8[8] =      { 0x66, 0x69, 0x6c, 0x65, 0x2d, 0xc3, 0xa9, 0 };
 	torture_assert(tctx, strncasecmp_m("foo", "bar", 3) != 0, "different strings");
 	torture_assert(tctx, strncasecmp_m("foo", "foo", 3) == 0, "same case strings");
 	torture_assert(tctx, strncasecmp_m("foo", "Foo", 3) == 0, "different case strings");
@@ -111,6 +121,8 @@ static bool test_strncasecmp_m(struct torture_context *tctx)
 	torture_assert(tctx, strncasecmp_m(NULL, "Foo", 3) != 0, "one NULL");
 	torture_assert(tctx, strncasecmp_m("foo", NULL, 3) != 0, "other NULL");
 	torture_assert(tctx, strncasecmp_m(NULL, NULL, 3) == 0, "both NULL");
+	torture_assert(tctx, strncasecmp_m(file_iso8859_1, file_utf8, 6) != 0,
+		"file.{accented e} should differ");
 	return true;
 }
 
--