From a30ac8d52cba121c3e28dcc2a01767f639bff665 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 1 Aug 2024 11:50:53 +0900
Subject: [PATCH] vmspawn: check overflow earlier

Follow-up for 862c68a914ab4561d83875e58e05dcf65cb4a551.
Fixes CID#1550749.
---
 src/vmspawn/vmspawn.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/vmspawn/vmspawn.c b/src/vmspawn/vmspawn.c
index 8fad195abcd..030efbdb23f 100644
--- a/src/vmspawn/vmspawn.c
+++ b/src/vmspawn/vmspawn.c
@@ -626,10 +626,10 @@ static int read_vsock_notify(NotifyConnectionData *d, int fd) {
                 if (n == 0) /* We hit EOF! Let's parse this */
                         break;
 
-                d->full += n;
-
-                if (d->full >= sizeof(d->buffer))
+                if ((size_t) n >= sizeof(d->buffer) - d->full)
                         return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Received notify message exceeded maximum size.");
+
+                d->full += n;
         }
 
         /* We reached EOF, now parse the thing */
-- 
2.47.3