Page MenuHomeFreeBSD
Files F143307867

D47286.id.diff
No OneTemporary
Actions

D47286.id.diff
View Options

diff --git a/include/string.h b/include/string.h
--- a/include/string.h
+++ b/include/string.h
@@ -71,6 +71,9 @@
void *(mempcpy)(void * __restrict, const void * __restrict, size_t);
#endif
void *(memset)(void *, int, size_t);
+#if __BSD_VISIBLE || __ISO_C_VISIBLE >= 2023
+void *memset_explicit(void *, int, size_t);
+#endif
#if __POSIX_VISIBLE >= 200809
char *(stpcpy)(char * __restrict, const char * __restrict);
char *(stpncpy)(char * __restrict, const char * __restrict, size_t);
diff --git a/lib/libc/string/Makefile.inc b/lib/libc/string/Makefile.inc
--- a/lib/libc/string/Makefile.inc
+++ b/lib/libc/string/Makefile.inc
@@ -11,6 +11,7 @@
ffs.c ffsl.c ffsll.c fls.c flsl.c flsll.c \
memccpy.c memchr.c memrchr.c memcmp.c \
memcpy.c memmem.c memmove.c mempcpy.c memset.c memset_s.c \
+ memset_explicit.c \
stpcpy.c stpncpy.c strcasecmp.c \
strcat.c strcasestr.c strchr.c strchrnul.c strcmp.c strcoll.c strcpy.c\
strcspn.c strdup.c strerror.c strlcat.c strlcpy.c strlen.c strmode.c \
@@ -62,7 +63,8 @@
MLINKS+=index.3 rindex.3
MLINKS+=memchr.3 memrchr.3
MLINKS+=memcpy.3 mempcpy.3
-MLINKS+=memset.3 memset_s.3
+MLINKS+=memset.3 memset_s.3 \
+ memset.3 memset_explicit.3
MLINKS+=strcasecmp.3 strncasecmp.3 \
strcasecmp.3 strcasecmp_l.3 \
strcasecmp.3 strncasecmp_l.3
diff --git a/lib/libc/string/Symbol.map b/lib/libc/string/Symbol.map
--- a/lib/libc/string/Symbol.map
+++ b/lib/libc/string/Symbol.map
@@ -116,6 +116,10 @@
wmempcpy;
};
+FBSD_1.8 {
+ memset_explicit;
+};
+
FBSDprivate_1.0 {
__strtok_r;
};
diff --git a/lib/libc/string/memset.3 b/lib/libc/string/memset.3
--- a/lib/libc/string/memset.3
+++ b/lib/libc/string/memset.3
@@ -29,7 +29,7 @@
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.Dd August 19, 2018
+.Dd October 24, 2024
.Dt MEMSET 3
.Os
.Sh NAME
@@ -41,6 +41,8 @@
.In string.h
.Ft void *
.Fn memset "void *dest" "int c" "size_t len"
+.Ft void *
+.Fn memset_explicit "void *dest" "int c" "size_t len"
.Fd #define __STDC_WANT_LIB_EXT1__ 1
.Ft errno_t
.Fn memset_s "void *dest" "rsize_t destsz" "int c" "rsize_t len"
@@ -68,6 +70,13 @@
is an invalid pointer.
.Pp
The
+.Fn memset_explicit
+function behaves the same as
+.Fn memset, but will not be removed by a compiler's dead store
+optimization pass, making it useful for clearing sensitive memory
+such as a password.
+.Pp
+The
.Fn memset_s
function behaves the same as
.Fn memset
@@ -108,7 +117,9 @@
.Sh RETURN VALUES
The
.Fn memset
-function returns its first argument.
+and
+.Fn memset_explicit
+functions return their first argument.
The
.Fn memset_s
function returns zero on success, non-zero on error.
@@ -128,3 +139,6 @@
conforms to
.St -isoC-2011
K.3.7.4.1.
+.Fn memset_explicit
+conforms to
+.St -isoC-2024 .
diff --git a/lib/libc/string/memset_explicit.c b/lib/libc/string/memset_explicit.c
new file mode 100644
--- /dev/null
+++ b/lib/libc/string/memset_explicit.c
@@ -0,0 +1,26 @@
+/*-
+ * SPDF-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Robert Clausecker <fuz@FreeBSD.org>
+ */
+
+#include <string.h>
+
+__attribute__((weak)) void __memset_explicit_hook(void *, int, size_t);
+
+__attribute__((weak)) void
+__memset_explicit_hook(void *buf, int ch, size_t len)
+{
+ (void)buf;
+ (void)ch;
+ (void)len;
+}
+
+void *
+memset_explicit(void *buf, int ch, size_t len)
+{
+ memset(buf, ch, len);
+ __memset_explicit_hook(buf, ch, len);
+
+ return (buf);
+}

File Metadata

Mime Type
text/plain
Expires
Thu, Jan 29, 5:33 PM (3 h, 40 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
28086284
Default Alt Text
D47286.id.diff (3 KB)

Event Timeline