From: 胡玮文 <huww98@outlook.com>
Date: Sat, 16 Mar 2024 11:33:44 +0000 (+0800)
Subject: common/Journald: fix alias and mis-align
X-Git-Tag: v20.0.0~1992^2~1
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=b4a96fa59dd610a935053b7ac97a1715bca27db2;p=ceph.git

common/Journald: fix alias and mis-align

by replacing assignment with memcpy.

The original version breaks the strict aliasing rule, and may be
mis-aligned, which may cause undefined behavior.

Signed-off-by: 胡玮文 <huww98@outlook.com>
---

diff --git a/src/common/Journald.cc b/src/common/Journald.cc
index a1321c7eea8e..983a190b1a70 100644
--- a/src/common/Journald.cc
+++ b/src/common/Journald.cc
@@ -125,7 +125,7 @@ MESSAGE
 
     uint64_t msg_len = htole64(e.size());
     meta_buf.resize(meta_buf.size() + sizeof(msg_len));
-    *(reinterpret_cast<uint64_t*>(meta_buf.end()) - 1) = htole64(e.size());
+    memcpy(meta_buf.end() - sizeof(msg_len), &msg_len, sizeof(msg_len));
 
     meta_vec().iov_base = meta_buf.data();
     meta_vec().iov_len = meta_buf.size();