From: Stefan Hajnoczi <stefanha@gmail.com>
To: "Daniel P. Berrangé" <berrange@redhat.com>
Cc: qemu-devel@nongnu.org,
Alex Williamson <alex.williamson@redhat.com>,
Gerd Hoffmann <kraxel@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v2 1/4] display: ensure qxl log_buf is a nul terminated string
Date: Mon, 21 Jan 2019 10:45:45 +0000 [thread overview]
Message-ID: <20190121104545.GE30536@stefanha-x1.localdomain> (raw)
In-Reply-To: <20190118173103.4903-2-berrange@redhat.com>
[-- Attachment #1: Type: text/plain, Size: 758 bytes --]
On Fri, Jan 18, 2019 at 05:31:00PM +0000, Daniel P. Berrangé wrote:
> diff --git a/hw/display/qxl.c b/hw/display/qxl.c
> index 8e9a65e75b..eefdf4baac 100644
> --- a/hw/display/qxl.c
> +++ b/hw/display/qxl.c
> @@ -1763,7 +1763,8 @@ async_common:
> qxl_set_mode(d, val, 0);
> break;
> case QXL_IO_LOG:
> - trace_qxl_io_log(d->id, d->ram->log_buf);
> + d->ram->log_buf[sizeof(d->ram->log_buf) - 1] = '\0';
> + trace_qxl_io_log(d->id, (const char *)d->ram->log_buf);
This is a PCI BAR shared with the guest? Then NUL termination is
subject to races with vcpu threads that modify log_buf[] while we access
it.
The safe way to do this is to copy in log_buf[] and then NUL-terminate
the local copy.
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 455 bytes --]
next prev parent reply other threads:[~2019-01-21 10:45 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-18 17:30 [Qemu-devel] [PATCH v2 0/4] trace: make systemtap easier to use for simple logging Daniel P. Berrangé
2019-01-18 17:31 ` [Qemu-devel] [PATCH v2 1/4] display: ensure qxl log_buf is a nul terminated string Daniel P. Berrangé
2019-01-18 17:40 ` Eric Blake
2019-01-18 17:42 ` Daniel P. Berrangé
2019-01-21 7:14 ` Gerd Hoffmann
2019-01-21 10:45 ` Stefan Hajnoczi [this message]
2019-01-22 14:17 ` Daniel P. Berrangé
2019-01-18 17:31 ` [Qemu-devel] [PATCH v2 2/4] trace: enforce that every trace-events file has a final newline Daniel P. Berrangé
2019-01-18 17:42 ` Eric Blake
2019-01-22 14:43 ` Daniel P. Berrangé
2019-01-21 10:47 ` Stefan Hajnoczi
2019-01-18 17:31 ` [Qemu-devel] [PATCH v2 3/4] trace: forbid use of %m in trace event format strings Daniel P. Berrangé
2019-01-18 17:50 ` Eric Blake
2019-01-18 22:50 ` Alex Williamson
2019-01-22 14:32 ` Daniel P. Berrangé
2019-01-22 17:19 ` Eric Blake
2019-01-22 17:23 ` Daniel P. Berrangé
2019-01-22 18:10 ` Eric Blake
2019-10-18 9:31 ` Thomas Huth
2019-10-18 9:34 ` Daniel P. Berrangé
2019-01-18 17:31 ` [Qemu-devel] [PATCH v2 4/4] trace: add ability to do simple printf logging via systemtap Daniel P. Berrangé
2019-01-18 18:14 ` Eric Blake
2019-01-21 10:53 ` Stefan Hajnoczi
2019-01-22 14:34 ` Daniel P. Berrangé
2019-01-22 14:39 ` Daniel P. Berrangé
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190121104545.GE30536@stefanha-x1.localdomain \
--to=stefanha@gmail.com \
--cc=alex.williamson@redhat.com \
--cc=berrange@redhat.com \
--cc=kraxel@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).