From: Ivan Grokhotkov <ivan@espressif.com>
Date: Thu, 19 Oct 2017 13:30:26 +0000 (+0800)
Subject: Merge branch 'bugfix/malloc_failure' into 'master'
X-Git-Tag: v3.1-dev~152
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6cc809961033c9007a4250c8401c2c7e41c99d7b;p=esp-idf

Merge branch 'bugfix/malloc_failure' into 'master'

heap: Fix race condition causing malloc() to fail under some conditions

See merge request !1424
---

6cc809961033c9007a4250c8401c2c7e41c99d7b
diff --cc components/heap/multi_heap.c
index 98aa425015,cc621c0d88..93ae0c5f67
--- a/components/heap/multi_heap.c
+++ b/components/heap/multi_heap.c
@@@ -351,8 -341,18 +351,18 @@@ void *multi_heap_malloc_impl(multi_heap
          return NULL;
      }
  
 -    MULTI_HEAP_LOCK(heap->lock);
 +    multi_heap_internal_lock(heap);
  
+     /* Note: this check must be done while holding the lock as both
+        malloc & realloc may temporarily shrink the free_bytes value
+        before they split a large block. This can result in false negatives,
+        especially if the heap is unfragmented.
+     */
+     if (heap->free_bytes < size) {
+         MULTI_HEAP_UNLOCK(heap->lock);
+         return NULL;
+     }
+ 
      /* Find best free block to perform the allocation in */
      prev = &heap->first_block;
      for (heap_block_t *b = heap->first_block.next_free; b != NULL; b = b->next_free) {