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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Li Feng <fengli@smartx.com>, Chenbo Xia <chenbo.xia@intel.com>
Cc: dev@dpdk.org
Subject: Re: [PATCH v3] vhost: avoid potential null pointer access
Date: Mon, 25 Sep 2023 10:15:13 +0200	[thread overview]
Message-ID: <7136f05c-023b-fda5-44ee-8a26b0c8e548@redhat.com> (raw)
In-Reply-To: <20230912074217.2480397-1-fengli@smartx.com>



On 9/12/23 09:42, Li Feng wrote:
> If the user calls rte_vhost_vring_call() on a ring that has been
> invalidated, we will encounter SEGV.
> 
> We should check the pointer firstly before accessing it.
> 
> Signed-off-by: Li Feng <fengli@smartx.com>
> ---
> v2 -> v3:
> - Also fix the rte_vhost_vring_call_nonblock.
> 
> v1 -> v2:
> - Fix rebase error.
> 
> 
> 
>   lib/vhost/vhost.c | 14 ++++++++------
>   lib/vhost/vhost.h | 12 ++++++++++--
>   2 files changed, 18 insertions(+), 8 deletions(-)


Thanks for posting the fix, the segmentation fault may indeed happen 
when injecting IRQ from the app directly using the Vhost API. It cannot
happen when vhost_vring_call() is calle directly from
rte_enqueue_burst/rte_dequeue_burst though.

so I think below patch would be better:

diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index eb6309b681..733e0ab289 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -1341,6 +1341,9 @@ rte_vhost_vring_call(int vid, uint16_t vring_idx)

         rte_rwlock_read_lock(&vq->access_lock);

+       if (unlikely(!vq->access_ok))
+               return -1;
+
         if (vq_is_packed(dev))
                 vhost_vring_call_packed(dev, vq);
         else
@@ -1371,6 +1374,9 @@ rte_vhost_vring_call_nonblock(int vid, uint16_t 
vring_idx)
         if (rte_rwlock_read_trylock(&vq->access_lock))
                 return -EAGAIN;

+       if (unlikely(!vq->access_ok))
+               return -1;
+
         if (vq_is_packed(dev))
                 vhost_vring_call_packed(dev, vq);
         else


Do you confirm that fixes your issue?

Thanks,
Maxime


  reply	other threads:[~2023-09-25  8:15 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-12  7:42 Li Feng
2023-09-25  8:15 ` Maxime Coquelin [this message]
2023-09-25  8:26   ` Maxime Coquelin
2023-09-25 10:37   ` Morten Brørup
2023-09-25 10:59     ` Maxime Coquelin

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