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From: | Jason Wang |
Subject: | Re: [PATCH-for-6.0] net: tap: fix crash on hotplug |
Date: | Thu, 22 Apr 2021 10:25:26 +0800 |
User-agent: | Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 |
在 2021/4/21 下午11:22, Cole Robinson 写道:
Attempting to hotplug a tap nic with libvirt will crash qemu: $ sudo virsh attach-interface f32 network default error: Failed to attach interface error: Unable to read from monitor: Connection reset by peer 0x000055875b7f3a99 in tap_send (opaque=0x55875e39eae0) at ../net/tap.c:206 206 if (!s->nc.peer->do_not_pad) { gdb$ bt s->nc.peer may not be set at this point. This seems to be an expected case, as qemu_send_packet_* explicitly checks for NULL s->nc.peer later. Fix it by checking for s->nc.peer here too. Padding is applied if s->nc.peer is not set. https://bugzilla.redhat.com/show_bug.cgi?id=1949786 Fixes: 969e50b61a2 Signed-off-by: Cole Robinson <crobinso@redhat.com> --- * Or should we skip padding if nc.peer is unset?
I think so, the padding is for the peer.
I didn't dig into it * tap-win3.c and slirp.c may need a similar fix, but the slirp case didn't crash in a simple test.
Yes, the reason is because there's no packet go through slirp I think. Thanks.
net/tap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/tap.c b/net/tap.c index dd42ac6134..937559dbb8 100644 --- a/net/tap.c +++ b/net/tap.c @@ -203,7 +203,7 @@ static void tap_send(void *opaque) size -= s->host_vnet_hdr_len; }- if (!s->nc.peer->do_not_pad) {+ if (!s->nc.peer || !s->nc.peer->do_not_pad) { if (eth_pad_short_frame(min_pkt, &min_pktsz, buf, size)) { buf = min_pkt; size = min_pktsz;
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