xref: /third_party/libxml2/backport-error-Don-t-move-past-current-position.patch

From d9a8dab3a3ba980f1efc1366c1b9a3a2434dcabd Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Sun, 22 Jan 2023 12:00:59 +0100
Subject: [PATCH] error: Don't move past current position

Make sure that we never move past the current position in
xmlParserPrintFileContextInternal.

Found with libFuzzer and -fsanitize=implicit-conversion.

Reference:https://github.com/GNOME/libxml2/commit/d9a8dab3a3ba980f1efc1366c1b9a3a2434dcabd
Conflict:NA
---
 error.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/error.c b/error.c
index fe9a7e2..5eee72a 100644
--- a/error.c
+++ b/error.c
@@ -188,10 +188,12 @@ xmlParserPrintFileContextInternal(xmlParserInputPtr input ,
     }
     n = 0;
     /* search backwards for beginning-of-line (to max buff size) */
-    while ((n++ < (sizeof(content)-1)) && (cur > base) &&
-	   (*(cur) != '\n') && (*(cur) != '\r'))
+    while ((n < sizeof(content) - 1) && (cur > base) &&
+	   (*cur != '\n') && (*cur != '\r')) {
         cur--;
-    if ((*(cur) == '\n') || (*(cur) == '\r')) {
+        n++;
+    }
+    if ((n > 0) && ((*cur == '\n') || (*cur == '\r'))) {
         cur++;
     } else {
         /* skip over continuation bytes */
-- 
2.27.0