From: Corinna Vinschen <vinschen@redhat.com>
To: Henrik Nilsson <henrik.nilsson@bytequest.se>
Cc: newlib@sourceware.org
Subject: Re: [PATCH] nano-mallocr: Prevent NULL pointer de-reference in free_list
Date: Mon, 27 Feb 2023 11:00:45 +0100 [thread overview]
Message-ID: <Y/x/TbegZ6424VZr@calimero.vinschen.de> (raw)
In-Reply-To: <Y/cO3Vkd2b1uQp8l@henrik-Latitude-5420>
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
prev parent reply other threads:[~2023-02-27 10:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-17 5:56 Henrik Nilsson
2023-02-23 6:59 ` Henrik Nilsson
2023-02-27 10:00 ` Corinna Vinschen [this message]
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