fix incorrect overflow check for allocation in fmemopen

[musl] / src / stdio / fmemopen.c

diff --git a/src/stdio/fmemopen.c b/src/stdio/fmemopen.c
index 7c193a5..2ce43d3 100644 (file)
--- a/src/stdio/fmemopen.c
+++ b/src/stdio/fmemopen.c
@@ -81,7 +81,7 @@ FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode)
                return 0;
        }
 
-       if (!buf && size > SIZE_MAX-sizeof(FILE)-BUFSIZ-UNGET) {
+       if (!buf && size > PTRDIFF_MAX) {
                errno = ENOMEM;
                return 0;
        }