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<p class="MsoNormal">Hi Mike,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks for your report.<o:p></o:p></p>
<p class="MsoNormal">I agree with you, maybe you can submit the patch to fix it. (by the way, the sync path has the same issue)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks a lot.<o:p></o:p></p>
<p class="MsoNormal">Cheng<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> Mike Cui <cuicui@gmail.com> <br>
<b>Sent:</b> Thursday, December 29, 2022 4:38 AM<br>
<b>To:</b> dev@dpdk.org; Jiang, Cheng1 <cheng1.jiang@intel.com><br>
<b>Subject:</b> lib/vhost/virtio_net: possible stack overflow in virtio_dev_tx_async_packed()<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi,<br>
<br>
I believe there is a possible stack overflow in this code: <a href="https://github.com/DPDK/dpdk/blob/main/lib/vhost/virtio_net.c#L3631">https://github.com/DPDK/dpdk/blob/main/lib/vhost/virtio_net.c#L3631</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Here, pkts_prealloc is declared on the stack with size MAX_PKT_BURST, then filled in by rte_pktmbuf_alloc_bulk() up to 'count' elements, but 'count' is not capped at MAX_PKT_BURST like in many other code paths.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Suggested patch:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="gmail-p1" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal">
<span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c</span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p1" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal">
<span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">index 9abf752f30..21f00317c7 100644</span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p1" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal">
<span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">--- a/lib/vhost/virtio_net.c</span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p1" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal">
<span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">+++ b/lib/vhost/virtio_net.c</span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p1" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal">
<span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">@@ -3634,6 +3634,7 @@ virtio_dev_tx_async_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,</span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p2" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;min-height:16px">
<span class="gmail-apple-converted-space"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"> </span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p1" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal">
<span class="gmail-apple-converted-space"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"> </span></span><span class="gmail-apple-tab-span"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">
</span></span><span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">async_iter_reset(async);</span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p2" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;min-height:16px">
<span class="gmail-apple-converted-space"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"> </span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p1" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal">
<span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">+</span></span><span class="gmail-apple-tab-span"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">
</span></span><span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">count = RTE_MIN(count, MAX_PKT_BURST);</span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p1" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal">
<span class="gmail-apple-converted-space"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"> </span></span><span class="gmail-apple-tab-span"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">
</span></span><span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">if (rte_pktmbuf_alloc_bulk(mbuf_pool, pkts_prealloc, count))</span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p1" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal">
<span class="gmail-apple-converted-space"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"> </span></span><span class="gmail-apple-tab-span"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">
</span></span><span class="gmail-s1"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black">goto out;</span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
<p class="gmail-p2" style="margin:0in;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;min-height:16px">
<span class="gmail-apple-converted-space"><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"> </span></span><span style="font-size:10.5pt;font-family:"Menlo",serif;color:black"><o:p></o:p></span></p>
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