From fd6ea0dfc94bd5160c31ddad843e3e175e6c1f61 Mon Sep 17 00:00:00 2001
From: Nicholas Wilson <nicholas@nicholaswilson.me.uk>
Date: Sat, 22 Aug 2026 12:24:26 +0100
Subject: [PATCH] pcre2grep: Fix small UBSan int overflow regression

---
 src/pcre2grep.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/pcre2grep.c b/src/pcre2grep.c
index 34d8089c1..613b35086 100644
--- a/src/pcre2grep.c
+++ b/src/pcre2grep.c
@@ -3151,11 +3151,20 @@ while (ptr < endptr)
 
           while (startoffset > linelength + endlinelength)
             {
-            ptr += linelength + endlinelength;
-            filepos += (int)(linelength + endlinelength);
+            PCRE2_SIZE lineadvance = linelength + endlinelength;
+
+            if (endprevious < lineadvance)
+              {
+              FWRITE_IGNORE(ptr + endprevious, 1,
+                lineadvance - endprevious, stdout);
+              endprevious = 0;
+              }
+            else endprevious -= lineadvance;
+
+            ptr += lineadvance;
+            filepos += (int)lineadvance;
             linenumber++;
-            startoffset -= (int)(linelength + endlinelength);
-            endprevious -= (int)(linelength + endlinelength);
+            startoffset -= lineadvance;
             t = end_of_line(ptr, endptr, &endlinelength);
             linelength = t - ptr - endlinelength;
             length = (PCRE2_SIZE)(endptr - ptr);