From 697a822f1e272f0548c2f3ffd5b67bb21df528bf Mon Sep 17 00:00:00 2001
From: Alexander Partanen <alex.pentagrid@gmail.com>
Date: Thu, 21 Nov 2024 17:25:54 +0300
Subject: [PATCH] ostream: fix potential overwrite in StrBuf::sync_impl

---
 src/plugins/output_format/ostream.cpp | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/plugins/output_format/ostream.cpp b/src/plugins/output_format/ostream.cpp
index d5f9ffaf3..0a7011a42 100644
--- a/src/plugins/output_format/ostream.cpp
+++ b/src/plugins/output_format/ostream.cpp
@@ -145,13 +145,15 @@ class StrBuf : public std::stringbuf
         // this is required because of printf() logging
         fflush(stdout);
 
-        for (auto size = pptr() - pbase(); size > 0; )
+        auto size_remains = pptr() - pbase();
+        char* current_position = pbase();
+        while (size_remains > 0)
         {
-            auto written = write(STDOUT_FILENO, pbase(), size);
+            ssize_t written = write(STDOUT_FILENO, current_position, size_remains);
             if (written < 0)
                 return -1;
-            size -= written;
-            seekoff(written, std::ios_base::cur, std::ios_base::out);
+            size_remains -= written;
+            current_position += written;
         }
         seekpos(0);
         return 0;