[PATCH 2/2] utf8: Fix expected bytes in l_utf8_get_codepoint

[Michael Tretter <michael.tretter@posteo.net>]

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UTF-8 requires the form 10xxxxxx for the second, third and forth bytes
of a well-formed byte sequences. Therefore, comparing with 0 is not
sufficient to exclude ill-formed byte sequences, but the first two bit
must follow the specified form.

Without this check, iwd crashes if it encounters Latin-1 Supplement
encoded SSIDs during scanning, because they are erroneously accepted as
valid UTF-8.
---
 ell/utf8.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ell/utf8.c b/ell/utf8.c
index e9998f7..f8750d8 100644
--- a/ell/utf8.c
+++ b/ell/utf8.c
@@ -109,7 +109,7 @@ LIB_EXPORT int l_utf8_get_codepoint(const char *str, size_t len, wchar_t *cp)
 	val = str[0] & (0xff >> (expect_bytes + 1));
 
 	for (i = 1; i < expect_bytes; i++) {
-		if ((str[i] & 0xc0) == 0)
+		if ((str[i] & 0xc0) != 0x80)
 			goto error;
 
 		val <<= 6;
-- 
2.21.0