From 22a8094b41b2606084dc0c0c70487e5ed0fcb652 Mon Sep 17 00:00:00 2001
From: jvoisin
Date: Wed, 27 Dec 2023 17:07:32 +0100
Subject: Re-enable previously disabled overlap checks

They were previously disabled in 80a83a5
---
 include/string.h | 29 ++++++++++++-----------------
 1 file changed, 12 insertions(+), 17 deletions(-)

(limited to 'include')

diff --git a/include/string.h b/include/string.h
index 9cb0598..75dadab 100644
--- a/include/string.h
+++ b/include/string.h
@@ -189,19 +189,17 @@ _FORTIFY_FN(stpncpy) char *stpncpy(char * _FORTIFY_POS0 __d, const char *__s,
 #if __has_builtin(__builtin___stpncpy_chk) && USE_NATIVE_CHK
 	return __builtin___stpncpy_chk(__d, __s, __n, __fh_bos(__d, 0));
 #else
-#if 0
-	// They check overlap across the whole range of the given length, but
-	// the given length is not what will actually be copied, rather it's
-	// the maximum length (if src is shorter, only length of src will be
-	// copied). This triggers false positives and traps where it shouldn't
-	// (e.g. in ICU tests).
-	if (__fh_overlap(__d, __s, __n))
+	__fh_size_t max_len_s = strnlen(__s, __n);
+	if (__fh_overlap(__d, max_len_s, __s, max_len_s))
 		__builtin_trap();
-#endif
 
+	// If the length strlen(src) is smaller than n, the remaining
+	// characters in the array pointed to by dest are filled with null
+	// bytes ('\0')
 	__fh_size_t __b = __fh_bos(__d, 0);
-	if (__n > __b && strlen(__s) + 1 > __b)
+	if (__n > __b)
 		__builtin_trap();
+
 	return __orig_stpncpy(__d, __s, __n);
 #endif
 }
@@ -297,19 +295,16 @@ _FORTIFY_FN(strncpy) char *strncpy(char * _FORTIFY_POS0 __d,
 #if __has_builtin(__builtin___strncpy_chk) && USE_NATIVE_CHK
 	return __builtin___strncpy_chk(__d, __s, __n, __fh_bos(__d, 0));
 #else
-#if 0
-	// They check overlap across the whole range of the given length, but
-	// the given length is not what will actually be copied, rather it's
-	// the maximum length (if src is shorter, only length of src will be
-	// copied). This triggers false positives and traps where it shouldn't
-	// (e.g. in ICU tests).
-	if (__fh_overlap(__d, __s, __n))
+	__fh_size_t max_len_s = strnlen(__s, __n);
+	if (__fh_overlap(__d, max_len_s, __s, max_len_s))
 		__builtin_trap();
-#endif
 
+	// If the length of src is less than n, strncpy() writes additional
+	// null bytes to dest to ensure that a total of n bytes are written.
 	__fh_size_t __b = __fh_bos(__d, 0);
 	if (__n > __b)
 		__builtin_trap();
+
 	return __orig_strncpy(__d, __s, __n);
 #endif
 }
-- 
cgit v1.3