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Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full |
Date: |
Thu, 4 Feb 2016 16:10:38 +0200 |
On Thu, Dec 03, 2015 at 10:53:17AM +0100, Didier Pallard wrote:
> unix_send_msgfds is used by vhost-user control socket. qemu_chr_fe_write_all
> is used to send a message and retries as long as EAGAIN errno is set,
> but write_msgfds buffer is freed after first EAGAIN failure, causing
> message to be sent without proper fds attachment.
>
> In case unix_send_msgfds is called through qemu_chr_fe_write, it will be
> user responsability to resend message as is or to free write_msgfds
> using set_msgfds(0)
>
> Signed-off-by: Didier Pallard <address@hidden>
> Reviewed-by: Thibaut Collet <address@hidden>
> ---
> qemu-char.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/qemu-char.c b/qemu-char.c
> index 5448b0f..26d5f2e 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -2614,6 +2614,16 @@ static int unix_send_msgfds(CharDriverState *chr,
> const uint8_t *buf, int len)
> r = sendmsg(s->fd, &msgh, 0);
> } while (r < 0 && errno == EINTR);
>
> + /* Ancillary data are not sent if no byte is written
> + * so don't free msgfds buffer if return value is EAGAIN
> + * If called from qemu_chr_fe_write_all retry will come soon
> + * If called from qemu_chr_fe_write, it is the user responsibility
> + * to resend message or free fds using set_msgfds(0)
Problem is, if ever anyone tries to send messages
with qemu_chr_fe_write and does not retry, there will
be a memory leak.
Rather than this, how about adding an assert in qemu_chr_fe_write
to make sure its not used with msgfds?
> + */
> + if (r < 0 && errno == EAGAIN) {
> + return r;
> + }
> +
> /* free the written msgfds, no matter what */
> if (s->write_msgfds_num) {
> g_free(s->write_msgfds);
> --
> 2.1.4
>
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Michael S. Tsirkin, 2016/02/04
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Didier Pallard, 2016/02/08
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Daniel P. Berrange, 2016/02/09
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Michael S. Tsirkin, 2016/02/09
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Didier Pallard, 2016/02/09
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Michael S. Tsirkin, 2016/02/09
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Daniel P. Berrange, 2016/02/09
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Didier Pallard, 2016/02/10
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Michael S. Tsirkin, 2016/02/10
- Re: [Qemu-devel] [PATCH 1/3] char: fix vhost-user socket full, Daniel P. Berrange, 2016/02/10