scc

commit 5ab34fe6b03c4e0938f17fe445e96bc19bf76768
parent 6bebff844a6aa4f95675dc7beae9ff24d06464b0
Author: Hiltjo Posthuma <hiltjo@codemadness.org>
Date:   Thu, 19 May 2022 18:53:46 +0200

libc: fix underflow in vsnprintf when size is 0

"If n is zero, nothing is written, and s may be a null pointer."

Diffstat:
M
src/libc/stdio/vsnprintf.c
 | 
3
++-

1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/libc/stdio/vsnprintf.c b/src/libc/stdio/vsnprintf.c
@@ -19,7 +19,8 @@ vsnprintf(char *restrict s, size_t siz, const char *restrict fmt, va_list ap)
 	if (s) {
 		if (f.wp == f.rp)
 			--f.wp;
-		*f.wp = '\0';
+		if (siz != 0)
+			*f.wp = '\0';
 	}
 
 	return r;