[PATCH 17/32] lib/string: Add KMSAN support to strlcpy() and strlcat()

Ilya Leoshkevich
2023-11-15T20:36:04Z

Currently KMSAN does not fully propagate metadata in strlcpy() and
strlcat(), because they are built with -ffreestanding and call
memcpy(). In this combination memcpy() calls are not instrumented.

Fix by copying the metadata manually. Add the __STDC_HOSTED__ #ifdef in
case the code is compiled with different flags in the future.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
lib/string.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/lib/string.c b/lib/string.c
index be26623953d2..e83c6dd77ec6 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -111,6 +111,9 @@ size_t strlcpy(char *dest, const char *src, size_t size)
if (size) {
size_t len = (ret >= size) ? size - 1 : ret;
__builtin_memcpy(dest, src, len);
+#if __STDC_HOSTED__ == 0
+ kmsan_memmove_metadata(dest, src, len);
+#endif
dest[len] = '\0';
}
return ret;
@@ -261,6 +264,9 @@ size_t strlcat(char *dest, const char *src, size_t count)
if (len >= count)
len = count-1;
__builtin_memcpy(dest, src, len);
+#if __STDC_HOSTED__ == 0
+ kmsan_memmove_metadata(dest, src, len);
+#endif
dest[len] = 0;
return res;
}
--
2.41.0