All of lore.kernel.org
 help / color / mirror / Atom feed
From: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
To: oleksandr_andrushchenko@epam.com, airlied@linux.ie, daniel@ffwll.ch
Cc: dri-devel@lists.freedesktop.org, xen-devel@lists.xenproject.org,
	linux-kernel@vger.kernel.org,
	Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Subject: [PATCH] gpu/xen: Fix a use after free in xen_drm_drv_init
Date: Mon, 22 Mar 2021 18:46:56 -0700	[thread overview]
Message-ID: <20210323014656.10068-1-lyl2019@mail.ustc.edu.cn> (raw)

In function displback_changed, has the call chain
displback_connect(front_info)->xen_drm_drv_init(front_info).
We can see that drm_info is assigned to front_info->drm_info
and drm_info is freed in fail branch in xen_drm_drv_init().

Later displback_disconnect(front_info) is called and it calls
xen_drm_drv_fini(front_info) cause a use after free by
drm_info = front_info->drm_info statement.

My patch has done two things. First fixes the fail label which
drm_info = kzalloc() failed and still free the drm_info.
Second sets front_info->drm_info to NULL to avoid uaf.

Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
---
 drivers/gpu/drm/xen/xen_drm_front.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c
index 30d9adf31c84..9f14d99c763c 100644
--- a/drivers/gpu/drm/xen/xen_drm_front.c
+++ b/drivers/gpu/drm/xen/xen_drm_front.c
@@ -521,7 +521,7 @@ static int xen_drm_drv_init(struct xen_drm_front_info *front_info)
 	drm_dev = drm_dev_alloc(&xen_drm_driver, dev);
 	if (IS_ERR(drm_dev)) {
 		ret = PTR_ERR(drm_dev);
-		goto fail;
+		goto fail_dev;
 	}
 
 	drm_info->drm_dev = drm_dev;
@@ -551,8 +551,10 @@ static int xen_drm_drv_init(struct xen_drm_front_info *front_info)
 	drm_kms_helper_poll_fini(drm_dev);
 	drm_mode_config_cleanup(drm_dev);
 	drm_dev_put(drm_dev);
-fail:
+fail_dev:
 	kfree(drm_info);
+	front_info->drm_info = NULL;
+fail:
 	return ret;
 }
 
-- 
2.25.1



WARNING: multiple messages have this Message-ID (diff)
From: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
To: oleksandr_andrushchenko@epam.com, airlied@linux.ie, daniel@ffwll.ch
Cc: xen-devel@lists.xenproject.org,
	Lv Yunlong <lyl2019@mail.ustc.edu.cn>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: [PATCH] gpu/xen: Fix a use after free in xen_drm_drv_init
Date: Mon, 22 Mar 2021 18:46:56 -0700	[thread overview]
Message-ID: <20210323014656.10068-1-lyl2019@mail.ustc.edu.cn> (raw)

In function displback_changed, has the call chain
displback_connect(front_info)->xen_drm_drv_init(front_info).
We can see that drm_info is assigned to front_info->drm_info
and drm_info is freed in fail branch in xen_drm_drv_init().

Later displback_disconnect(front_info) is called and it calls
xen_drm_drv_fini(front_info) cause a use after free by
drm_info = front_info->drm_info statement.

My patch has done two things. First fixes the fail label which
drm_info = kzalloc() failed and still free the drm_info.
Second sets front_info->drm_info to NULL to avoid uaf.

Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
---
 drivers/gpu/drm/xen/xen_drm_front.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c
index 30d9adf31c84..9f14d99c763c 100644
--- a/drivers/gpu/drm/xen/xen_drm_front.c
+++ b/drivers/gpu/drm/xen/xen_drm_front.c
@@ -521,7 +521,7 @@ static int xen_drm_drv_init(struct xen_drm_front_info *front_info)
 	drm_dev = drm_dev_alloc(&xen_drm_driver, dev);
 	if (IS_ERR(drm_dev)) {
 		ret = PTR_ERR(drm_dev);
-		goto fail;
+		goto fail_dev;
 	}
 
 	drm_info->drm_dev = drm_dev;
@@ -551,8 +551,10 @@ static int xen_drm_drv_init(struct xen_drm_front_info *front_info)
 	drm_kms_helper_poll_fini(drm_dev);
 	drm_mode_config_cleanup(drm_dev);
 	drm_dev_put(drm_dev);
-fail:
+fail_dev:
 	kfree(drm_info);
+	front_info->drm_info = NULL;
+fail:
 	return ret;
 }
 
-- 
2.25.1


_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

             reply	other threads:[~2021-03-23  1:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-23  1:46 Lv Yunlong [this message]
2021-03-23  1:46 ` [PATCH] gpu/xen: Fix a use after free in xen_drm_drv_init Lv Yunlong
2021-03-25  6:53 ` Oleksandr Andrushchenko
2021-03-25  6:53   ` Oleksandr Andrushchenko

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=20210323014656.10068-1-lyl2019@mail.ustc.edu.cn \
    --to=lyl2019@mail.ustc.edu.cn \
    --cc=airlied@linux.ie \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=oleksandr_andrushchenko@epam.com \
    --cc=xen-devel@lists.xenproject.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.