[GitHub] [incubator-nuttx] xiaoxiang781216 commented on a change in pull request #4765: mm: fix realloc overwrite memcpy when use a new block

[GitBox <gi...@apache.org>]

xiaoxiang781216 commented on a change in pull request #4765:
URL: https://github.com/apache/incubator-nuttx/pull/4765#discussion_r740186030



##########
File path: mm/mm_heap/mm_realloc.c
##########
@@ -355,7 +355,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
       newmem = (FAR void *)mm_malloc(heap, size);
       if (newmem)
         {
-          memcpy(newmem, oldmem, oldsize);
+          memcpy(newmem, oldmem, oldsize - SIZEOF_MM_ALLOCNODE);

Review comment:
       No, the problem isn't fee, but memcpy. oldsize include the house keeping data(SIZEOF_MM_ALLOCNODE) before oldmem, memcpy with oldsize will overwrite SIZEOF_MM_ALLOCNODE bytes of the next region.




-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: commits-unsubscribe@nuttx.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org