From d9528c265b96a5a0f0c2e43ac74ab3921a2987e1 Mon Sep 17 00:00:00 2001
From: Lorenz Kästle <12514511+RincewindsHat@users.noreply.github.com>
Date: Mon, 30 Jan 2023 12:45:20 +0100
Subject: check_http: Fix memory reallocation error in chunk decoding logic

This patch should fix an error with the way memory reallocation was
used, which resulted in "realloc(): invalid next size".
It is not completely clear to me as to what caused this problem, but
apparently one can not depend handing a pointer to "realloc(3)" and
expect that it still works afterwards, but one should/must use the one
returned by the function.

Also this patch replaces a variable which was used to remember the
position in the array by just computing that from the current values.
---
 plugins/check_http.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/plugins/check_http.c b/plugins/check_http.c
index a9c22389..c23625e9 100644
--- a/plugins/check_http.c
+++ b/plugins/check_http.c
@@ -1399,7 +1399,6 @@ char *unchunk_content(const char *content) {
   char *endptr;
   long length_of_chunk = 0;
   size_t overall_size = 0;
-  char *result_ptr;
 
   while (true) {
     size_of_chunk = strtol(pointer, &endptr, 16);
@@ -1446,7 +1445,6 @@ char *unchunk_content(const char *content) {
         }
         return NULL;
       }
-      result_ptr = result;
     } else {
       void *tmp = realloc(result, overall_size);
       if (tmp == NULL) {
@@ -1454,11 +1452,12 @@ char *unchunk_content(const char *content) {
           printf("Failed to allocate memory for unchunked body\n");
         }
         return NULL;
+      } else {
+        result = tmp;
       }
     }
 
-    memcpy(result_ptr, start_of_chunk, size_of_chunk);
-    result_ptr = result_ptr + size_of_chunk;
+    memcpy(result + (overall_size - size_of_chunk), start_of_chunk, size_of_chunk);
   }
 
   result[overall_size] = '\0';
-- 
cgit v1.2.3-74-g34f1


From d3fbcd122012af7733de3b80a692f79ad69057b2 Mon Sep 17 00:00:00 2001
From: Lorenz Kästle <12514511+RincewindsHat@users.noreply.github.com>
Date: Mon, 30 Jan 2023 13:33:46 +0100
Subject: check_http: Add space for ending NULL byte in array for chunked
 encoding

---
 plugins/check_http.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/plugins/check_http.c b/plugins/check_http.c
index c23625e9..5fa310f5 100644
--- a/plugins/check_http.c
+++ b/plugins/check_http.c
@@ -1438,7 +1438,8 @@ char *unchunk_content(const char *content) {
     overall_size += length_of_chunk;
 
     if (result == NULL) {
-      result = (char *)calloc(length_of_chunk, sizeof(char));
+      // Size of the chunk plus the ending NULL byte
+      result = (char *)malloc(length_of_chunk +1);
       if (result == NULL) {
         if (verbose) {
           printf("Failed to allocate memory for unchunked body\n");
@@ -1446,7 +1447,8 @@ char *unchunk_content(const char *content) {
         return NULL;
       }
     } else {
-      void *tmp = realloc(result, overall_size);
+      // Enlarge memory to the new size plus the ending NULL byte
+      void *tmp = realloc(result, overall_size +1);
       if (tmp == NULL) {
         if (verbose) {
           printf("Failed to allocate memory for unchunked body\n");
-- 
cgit v1.2.3-74-g34f1