From 8cbd12b9b776caa88b9bc9b91a8324d3afe2a321 Mon Sep 17 00:00:00 2001
From: Angus Gratton <angus@espressif.com>
Date: Tue, 31 Jul 2018 14:51:40 +1000
Subject: [PATCH] heap: When verifying & swapping a fill pattern, stop swapping
 if verification fails

Avoids situation where data has been overwritten during any post-mortem analysis
(core dump, gdbstub, etc).

As reported via forum https://esp32.com/viewtopic.php?f=2&t=6471&p=27790
---
 components/heap/multi_heap_poisoning.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/components/heap/multi_heap_poisoning.c b/components/heap/multi_heap_poisoning.c
index 3c8cff2410..dabf6cc241 100644
--- a/components/heap/multi_heap_poisoning.c
+++ b/components/heap/multi_heap_poisoning.c
@@ -147,6 +147,12 @@ static bool verify_fill_pattern(void *data, size_t size, bool print_errors, bool
                     MULTI_HEAP_STDERR_PRINTF("CORRUPT HEAP: Invalid data at %p. Expected 0x%08x got 0x%08x\n", p, EXPECT_WORD, *p);
                 }
                 valid = false;
+#ifndef NDEBUG
+                /* If an assertion is going to fail as soon as we're done verifying the pattern, leave the rest of the
+                   buffer contents as-is for better post-mortem analysis
+                */
+                swap_pattern = false;
+#endif
             }
             if (swap_pattern) {
                 *p = REPLACE_WORD;
@@ -164,6 +170,9 @@ static bool verify_fill_pattern(void *data, size_t size, bool print_errors, bool
                 MULTI_HEAP_STDERR_PRINTF("CORRUPT HEAP: Invalid data at %p. Expected 0x%02x got 0x%02x\n", p, (uint8_t)EXPECT_WORD, *p);
             }
             valid = false;
+#ifndef NDEBUG
+            swap_pattern = false; // same as above
+#endif
         }
         if (swap_pattern) {
             p[i] = (uint8_t)REPLACE_WORD;