Intel-GFX Archive on lore.kernel.org
 help / color / mirror / Atom feed
From: Pan Bian <bianpan2016@163.com>
To: Zhenyu Wang <zhenyuw@linux.intel.com>,
	Zhi Wang <zhi.a.wang@intel.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gvt-dev@lists.freedesktop.org,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org, Pan Bian <bianpan2016@163.com>
Subject: [PATCH] drm/i915/gvt: fix dropping obj reference twice
Date: Wed,  6 Nov 2019 15:31:07 +0800	[thread overview]
Message-ID: <1573025467-18278-1-git-send-email-bianpan2016@163.com> (raw)

The reference count of obj will be decremented twice if error occurs
in dma_buf_fd(). Additionally, attempting to read the reference count of
obj after dropping reference may lead to a use after free bug. Here, we
drop obj's reference until it is not used.

Signed-off-by: Pan Bian <bianpan2016@163.com>
---
 drivers/gpu/drm/i915/gvt/dmabuf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/dmabuf.c b/drivers/gpu/drm/i915/gvt/dmabuf.c
index 13044c027f27..4bfaefdf548d 100644
--- a/drivers/gpu/drm/i915/gvt/dmabuf.c
+++ b/drivers/gpu/drm/i915/gvt/dmabuf.c
@@ -498,8 +498,6 @@ int intel_vgpu_get_dmabuf(struct intel_vgpu *vgpu, unsigned int dmabuf_id)
 		goto out_free_gem;
 	}
 
-	i915_gem_object_put(obj);
-
 	ret = dma_buf_fd(dmabuf, DRM_CLOEXEC | DRM_RDWR);
 	if (ret < 0) {
 		gvt_vgpu_err("create dma-buf fd failed ret:%d\n", ret);
@@ -524,6 +522,8 @@ int intel_vgpu_get_dmabuf(struct intel_vgpu *vgpu, unsigned int dmabuf_id)
 		    file_count(dmabuf->file),
 		    kref_read(&obj->base.refcount));
 
+	i915_gem_object_put(obj);
+
 	return dmabuf_fd;
 
 out_free_dmabuf:
-- 
2.7.4

WARNING: multiple messages have this Message-ID (diff)
From: Pan Bian <bianpan2016@163.com>
To: Zhenyu Wang <zhenyuw@linux.intel.com>,
	Zhi Wang <zhi.a.wang@intel.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>
Cc: Pan Bian <bianpan2016@163.com>,
	intel-gfx@lists.freedesktop.org,
	intel-gvt-dev@lists.freedesktop.org,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: [Intel-gfx] [PATCH] drm/i915/gvt: fix dropping obj reference twice
Date: Wed,  6 Nov 2019 15:31:07 +0800	[thread overview]
Message-ID: <1573025467-18278-1-git-send-email-bianpan2016@163.com> (raw)
Message-ID: <20191106073107.Bfh204pt-Gdqza0mxvkP5YqkMmd0AsAhPf1X2evxGBE@z> (raw)

The reference count of obj will be decremented twice if error occurs
in dma_buf_fd(). Additionally, attempting to read the reference count of
obj after dropping reference may lead to a use after free bug. Here, we
drop obj's reference until it is not used.

Signed-off-by: Pan Bian <bianpan2016@163.com>
---
 drivers/gpu/drm/i915/gvt/dmabuf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/dmabuf.c b/drivers/gpu/drm/i915/gvt/dmabuf.c
index 13044c027f27..4bfaefdf548d 100644
--- a/drivers/gpu/drm/i915/gvt/dmabuf.c
+++ b/drivers/gpu/drm/i915/gvt/dmabuf.c
@@ -498,8 +498,6 @@ int intel_vgpu_get_dmabuf(struct intel_vgpu *vgpu, unsigned int dmabuf_id)
 		goto out_free_gem;
 	}
 
-	i915_gem_object_put(obj);
-
 	ret = dma_buf_fd(dmabuf, DRM_CLOEXEC | DRM_RDWR);
 	if (ret < 0) {
 		gvt_vgpu_err("create dma-buf fd failed ret:%d\n", ret);
@@ -524,6 +522,8 @@ int intel_vgpu_get_dmabuf(struct intel_vgpu *vgpu, unsigned int dmabuf_id)
 		    file_count(dmabuf->file),
 		    kref_read(&obj->base.refcount));
 
+	i915_gem_object_put(obj);
+
 	return dmabuf_fd;
 
 out_free_dmabuf:
-- 
2.7.4

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

             reply	other threads:[~2019-11-06  7:31 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06  7:31 Pan Bian [this message]
2019-11-06  7:31 ` [Intel-gfx] [PATCH] drm/i915/gvt: fix dropping obj reference twice Pan Bian
2019-11-06  8:43 ` Zhenyu Wang
2019-11-06  8:43   ` [Intel-gfx] " Zhenyu Wang
2019-11-06 22:27 ` ✓ Fi.CI.BAT: success for " Patchwork
2019-11-06 22:27   ` [Intel-gfx] " Patchwork
2019-11-08  0:02 ` ✓ Fi.CI.IGT: " Patchwork
2019-11-08  0:02   ` [Intel-gfx] " Patchwork

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=1573025467-18278-1-git-send-email-bianpan2016@163.com \
    --to=bianpan2016@163.com \
    --cc=airlied@linux.ie \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=intel-gfx@lists.freedesktop.org \
    --cc=intel-gvt-dev@lists.freedesktop.org \
    --cc=jani.nikula@linux.intel.com \
    --cc=joonas.lahtinen@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=rodrigo.vivi@intel.com \
    --cc=zhenyuw@linux.intel.com \
    --cc=zhi.a.wang@intel.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