"Richard W.M. Jones" <rjo...@redhat.com> writes:
> On Wed, Sep 05, 2012 at 02:01:36PM -0500, Anthony Liguori wrote:
>> Commit c3767ed0eb5d0bb25fe409ae5dec06e3411ff1b6 introduced a possible SEGV
>> when
>> using a socket chardev with server=on because it assumes that all TCP sockets
>> are in client mode.
>>
>> This patch adds a check to only reconnect when in client mode.
>>
>> Cc: Lei Li <li...@linux.vnet.ibm.com>
>> Reported-by: Michael Roth <mdr...@linux.vnet.ibm.com>
>> Signed-off-by: Anthony Liguori <aligu...@us.ibm.com>
>> ---
>> qemu-char.c | 4 +++-
>> 1 files changed, 3 insertions(+), 1 deletions(-)
>>
>> diff --git a/qemu-char.c b/qemu-char.c
>> index 398baf1..767da93 100644
>> --- a/qemu-char.c
>> +++ b/qemu-char.c
>> @@ -2148,10 +2148,12 @@ static int tcp_chr_write(CharDriverState *chr, const
>> uint8_t *buf, int len)
>> TCPCharDriver *s = chr->opaque;
>> if (s->connected) {
>> return send_all(s->fd, buf, len);
>> - } else {
>> + } else if (s->listen_fd == -1) {
>> /* (Re-)connect for unconnected writing */
>> tcp_chr_connect(chr);
>> return 0;
>> + } else {
>> + return len;
>> }
>> }
>
> Hi Anthony,
>
> I just came around this patch when I was trying to fix this
> bug: https://bugzilla.redhat.com/show_bug.cgi?id=853408
> qemu segfaults when trying to write to a serial socket which
> is *not* a server socket and has been closed by the other end.
>
> Unfortunately your patch above does not fix it. Only a
> complete revert of c3767ed0eb5d0 fixes it.
>
> I don't understand the purpose of c3767ed0eb5d0 at all. It
> seems to set the s->connected flag and carries on regardless,
> happily calling write (-1, ...), which is completely broken.
>
> The other end closed the socket. There's no one listening on the
> other end, and setting the s->connected flag will not help that.
You're 100% correct. I was only attempting to fix the server SEGV, I
didn't notice that client was hopelessly broken too. Will send a patch
reverting both commits.
Regards,
Anthony Liguori
>
> Rich.
>
> --
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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