> -----Original Message-----
> From: Honnappa Nagarahalli [mailto:honnappa.nagaraha...@arm.com]
> Sent: Wednesday, April 19, 2023 7:53 AM
> To: wangyunjian <wangyunj...@huawei.com>; dev@dpdk.org
> Cc: konstantin.v.anan...@yandex.ru; luyicai <luyi...@huawei.com>;
> sta...@dpdk.org; nd <n...@arm.com>; Honnappa Nagarahalli
> <honnappa.nagaraha...@arm.com>; nd <n...@arm.com>
> Subject: RE: [dpdk-dev] [PATCH] ring: fix use after free in ring release
>
>
>
> > -----Original Message-----
> > From: Yunjian Wang <wangyunj...@huawei.com>
> > Sent: Monday, April 17, 2023 8:12 AM
> > To: dev@dpdk.org
> > Cc: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>;
> > konstantin.v.anan...@yandex.ru; luyi...@huawei.com; Yunjian Wang
> > <wangyunj...@huawei.com>; sta...@dpdk.org
> > Subject: [dpdk-dev] [PATCH] ring: fix use after free in ring release
> >
> > When using the ring to find out tailq entry, however it had been freed
> > by rte_memzone_free function. This change prevents that from happening.
> I am unable to follow the problem you are describing.
> After the memzone for the ring is released, the contents of the memzone are
> not being used. I understand that the variable 'r' is being used, but that
> should
> not cause any issues.
>
> >
> > Fixes: 4e32101f9b01 ("ring: support freeing")
> > Cc: sta...@dpdk.org
> >
> > Signed-off-by: Yunjian Wang <wangyunj...@huawei.com>
> > ---
> > lib/ring/rte_ring.c | 11 +++++------
> > 1 file changed, 5 insertions(+), 6 deletions(-)
> >
> > diff --git a/lib/ring/rte_ring.c b/lib/ring/rte_ring.c index
> > 8ed455043d..17d2d7f8a8 100644
> > --- a/lib/ring/rte_ring.c
> > +++ b/lib/ring/rte_ring.c
> > @@ -333,11 +333,6 @@ rte_ring_free(struct rte_ring *r)
> > return;
> > }
> >
> > - if (rte_memzone_free(r->memzone) != 0) {
> > - RTE_LOG(ERR, RING, "Cannot free memory\n");
> > - return;
> > - }
> Why do we need to free the memzone later?
After the memzone is freed, it is not removed from the 'rte_ring_tailq'.
If rte_ring_lookup is called at this time, it will cause a use-after-free
problem.
Thanks,
Yunjian
>
> > -
> > ring_list = RTE_TAILQ_CAST(rte_ring_tailq.head, rte_ring_list);
> > rte_mcfg_tailq_write_lock();
> >
> > @@ -349,7 +344,7 @@ rte_ring_free(struct rte_ring *r)
> >
> > if (te == NULL) {
> > rte_mcfg_tailq_write_unlock();
> > - return;
> > + goto free_memzone;
> > }
> >
> > TAILQ_REMOVE(ring_list, te, next);
> > @@ -357,6 +352,10 @@ rte_ring_free(struct rte_ring *r)
> > rte_mcfg_tailq_write_unlock();
> >
> > rte_free(te);
> > +
> > +free_memzone:
> > + if (rte_memzone_free(r->memzone) != 0)
> > + RTE_LOG(ERR, RING, "Cannot free memory\n");
> > }
> >
> > /* dump the status of the ring on the console */
> > --
> > 2.33.0
