From: Jason A. Donenfeld <Jason@zx2c4.com>
Date: Mon, 25 Jan 2021 20:22:36 +0000 (+0100)
Subject: ipc: do not use fscanf with trailing \n
X-Git-Tag: v1.0.20210223~3
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=457f96b65e4f7241aceaa7cb9c7bbce7be1a2212;p=thirdparty%2Fwireguard-tools.git

ipc: do not use fscanf with trailing \n

If the stream is not closed, then this winds up hanging forever. So
remove the trailing \n\n and check manually after.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---

diff --git a/src/ipc-uapi.h b/src/ipc-uapi.h
index f464be7..d2ba522 100644
--- a/src/ipc-uapi.h
+++ b/src/ipc-uapi.h
@@ -92,8 +92,10 @@ static int userspace_set_device(struct wgdevice *dev)
 	fprintf(f, "\n");
 	fflush(f);
 
-	if (fscanf(f, "errno=%d\n\n", &ret) != 1)
+	if (fscanf(f, "errno=%d", &ret) != 1)
 		ret = errno ? -errno : -EPROTO;
+	if (getc(f) != '\n' || getc(f) != '\n')
+		ret = -EPROTO;
 	fclose(f);
 	errno = -ret;
 	return ret;