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nano-mallocr: Prevent NULL pointer de-reference in free_list 

The existing code checked if there was a chunk in free_list and
that the tail was not the next chunk.

The check if there is a chunk is not needed since it's already
known but the case of a single chunk in free_list needs to be
handled differently.
This commit is contained in:
Henrik Nilsson via Newlib 2023-02-17 06:56:49 +01:00 committed by Corinna Vinschen
parent 5011c8cc48
commit c8397ae817
1 changed files with 14 additions and 5 deletions
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15
newlib/libc/stdlib/nano-mallocr.c
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@ -333,14 +333,23 @@ void * nano_malloc(RARG malloc_size_t s)
{
p->size += alloc_size;
/* Remove chunk from free_list */
/* Remove chunk from free_list. Since p != NULL there is
at least one chunk */
r = free_list;
while (r && p != r->next)
if (r->next == NULL)
{
/* There is only a single chunk, remove it */
free_list = NULL;
}
else
{
/* Search for the chunk before the one to be removed */
while (p != r->next)
{
r = r->next;
}
r->next = NULL;
}
r = p;
}
else