* [PATCH] nano-mallocr: Prevent NULL pointer de-reference in free_list
@ 2023-02-17 5:56 Henrik Nilsson
2023-02-23 6:59 ` Henrik Nilsson
0 siblings, 1 reply; 3+ messages in thread
From: Henrik Nilsson @ 2023-02-17 5:56 UTC (permalink / raw)
To: newlib; +Cc: Henrik Nilsson
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.
---
newlib/libc/stdlib/nano-mallocr.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/newlib/libc/stdlib/nano-mallocr.c b/newlib/libc/stdlib/nano-mallocr.c
index b2273ba60..a2b50facc 100644
--- a/newlib/libc/stdlib/nano-mallocr.c
+++ b/newlib/libc/stdlib/nano-mallocr.c
@@ -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)
{
- r = r->next;
+ /* 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->next = NULL;
-
r = p;
}
else
--
2.34.1
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] nano-mallocr: Prevent NULL pointer de-reference in free_list
2023-02-17 5:56 [PATCH] nano-mallocr: Prevent NULL pointer de-reference in free_list Henrik Nilsson
@ 2023-02-23 6:59 ` Henrik Nilsson
2023-02-27 10:00 ` Corinna Vinschen
0 siblings, 1 reply; 3+ messages in thread
From: Henrik Nilsson @ 2023-02-23 6:59 UTC (permalink / raw)
To: newlib
On Fri, Feb 17, 2023 at 06:56:49AM +0100, Henrik Nilsson wrote:
> 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.
> ---
> newlib/libc/stdlib/nano-mallocr.c | 19 ++++++++++++++-----
> 1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/newlib/libc/stdlib/nano-mallocr.c b/newlib/libc/stdlib/nano-mallocr.c
> index b2273ba60..a2b50facc 100644
> --- a/newlib/libc/stdlib/nano-mallocr.c
> +++ b/newlib/libc/stdlib/nano-mallocr.c
> @@ -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)
> {
> - r = r->next;
> + /* 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->next = NULL;
> -
> r = p;
> }
> else
> --
> 2.34.1
>
Any comment on this patch?
BR,
Henrik
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] nano-mallocr: Prevent NULL pointer de-reference in free_list
2023-02-23 6:59 ` Henrik Nilsson
@ 2023-02-27 10:00 ` Corinna Vinschen
0 siblings, 0 replies; 3+ messages in thread
From: Corinna Vinschen @ 2023-02-27 10:00 UTC (permalink / raw)
To: Henrik Nilsson; +Cc: newlib
On Feb 23 07:59, Henrik Nilsson via Newlib wrote:
> On Fri, Feb 17, 2023 at 06:56:49AM +0100, Henrik Nilsson wrote:
> > 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.
> > ---
> > newlib/libc/stdlib/nano-mallocr.c | 19 ++++++++++++++-----
> > 1 file changed, 14 insertions(+), 5 deletions(-)
> >
> > diff --git a/newlib/libc/stdlib/nano-mallocr.c b/newlib/libc/stdlib/nano-mallocr.c
> > index b2273ba60..a2b50facc 100644
> > --- a/newlib/libc/stdlib/nano-mallocr.c
> > +++ b/newlib/libc/stdlib/nano-mallocr.c
> > @@ -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)
> > {
> > - r = r->next;
> > + /* 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->next = NULL;
> > -
> > r = p;
> > }
> > else
> > --
> > 2.34.1
> >
> Any comment on this patch?
Pushed.
Thanks,
Corinna
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-02-17 5:56 [PATCH] nano-mallocr: Prevent NULL pointer de-reference in free_list Henrik Nilsson
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