From 79a9938d843d38a64d7a17006cf5ad4335aa5b51 Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Wed, 13 Dec 2023 17:25:37 +0100
Subject: [PATCH] parser: Don't grow or shrink pull parser memory buffers

Readd check for memory buffers without a read callback to avoid
XML_MAX_LOOKUP_LIMIT errors if users provide a custom input buffer.
Regressed with commit 834b8123 and later changes.
---
 parserInternals.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/parserInternals.c b/parserInternals.c
index 693cfd6d..241329cd 100644
--- a/parserInternals.c
+++ b/parserInternals.c
@@ -584,6 +584,9 @@ xmlParserGrow(xmlParserCtxtPtr ctxt) {
     /* Don't grow push parser buffer. */
     if ((ctxt->progressive) && (ctxt->inputNr <= 1))
         return(0);
+    /* Don't grow memory buffers. */
+    if ((buf->encoder == NULL) && (buf->readcallback == NULL))
+        return(0);
     if (buf->error != 0)
         return(-1);
 
@@ -633,6 +636,10 @@ xmlParserInputGrow(xmlParserInputPtr in, int len) {
     if (in->cur == NULL) return(-1);
     if (in->buf->buffer == NULL) return(-1);
 
+    /* Don't grow memory buffers. */
+    if ((in->buf->encoder == NULL) && (in->buf->readcallback == NULL))
+        return(0);
+
     indx = in->cur - in->base;
     if (xmlBufUse(in->buf->buffer) > (unsigned int) indx + INPUT_CHUNK) {
         return(0);
@@ -666,6 +673,11 @@ xmlParserShrink(xmlParserCtxtPtr ctxt) {
 
     if (buf == NULL)
         return;
+    /* Don't shrink pull parser memory buffers. */
+    if (((ctxt->progressive == 0) || (ctxt->inputNr > 1)) &&
+        (buf->encoder == NULL) &&
+        (buf->readcallback == NULL))
+        return;
 
     used = in->cur - in->base;
     /*