linux-kernel - [PATCH 4.2.y-ckt 024/305] drm/i915: Don't clobber the addfb2 ioctl params

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Message-Id: <1452902519-2754-25-git-send-email-kamal@canonical.com>
Date:	Fri, 15 Jan 2016 15:57:18 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Daniel Vetter <daniel.vetter@...ll.ch>,
	Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
	Ville Syrjälä 
	<ville.syrjala@...ux.intel.com>,
	Jani Nikula <jani.nikula@...el.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 024/305] drm/i915: Don't clobber the addfb2 ioctl params

4.2.8-ckt2 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@...ux.intel.com>

commit 76dc3769d7c3cdcfa7c4c7768a7cb87cd91af12f upstream.

We try to convert the old way of of specifying fb tiling (obj->tiling)
into the new fb modifiers. We store the result in the passed in mode_cmd
structure. But that structure comes directly from the addfb2 ioctl, and
gets copied back out to userspace, which means we're clobbering the
modifiers that the user provided (all 0 since the DRM_MODE_FB_MODIFIERS
flag wasn't even set by the user). Hence if the user reuses the struct
for another addfb2, the ioctl will be rejected since it's now asking for
some modifiers w/o the flag set.

Fix the problem by making a copy of the user provided structure. We can
play any games we want with the copy.

IGT-Version: 1.12-git (x86_64) (Linux: 4.4.0-rc1-stereo+ x86_64)
...
Subtest basic-X-tiled: SUCCESS (0.001s)
Test assertion failure function pitch_tests, file kms_addfb_basic.c:167:
Failed assertion: drmIoctl(fd, DRM_IOCTL_MODE_ADDFB2, &f) == 0
Last errno: 22, Invalid argument
Stack trace:
  #0 [__igt_fail_assert+0x101]
  #1 [pitch_tests+0x619]
  #2 [__real_main426+0x2f]
  #3 [main+0x23]
  #4 [__libc_start_main+0xf0]
  #5 [_start+0x29]
  #6 [<unknown>+0x29]
  Subtest framebuffer-vs-set-tiling failed.
  **** DEBUG ****
  Test assertion failure function pitch_tests, file kms_addfb_basic.c:167:
  Failed assertion: drmIoctl(fd, DRM_IOCTL_MODE_ADDFB2, &f) == 0
  Last errno: 22, Invalid argument
  ****  END  ****
  Subtest framebuffer-vs-set-tiling: FAIL (0.003s)
  ...

IGT-Version: 1.12-git (x86_64) (Linux: 4.4.0-rc1-stereo+ x86_64)
Subtest framebuffer-vs-set-tiling: SUCCESS (0.000s)

Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Fixes: 2a80eada326f ("drm/i915: Add fb format modifier support")
Testcase: igt/kms_addfb_basic/clobbered-modifier
Signed-off-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1447261890-3960-1-git-send-email-ville.syrjala@linux.intel.com
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/gpu/drm/i915/intel_display.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 375ded3..05bf98d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14265,16 +14265,17 @@ static int intel_framebuffer_init(struct drm_device *dev,
 static struct drm_framebuffer *
 intel_user_framebuffer_create(struct drm_device *dev,
 			      struct drm_file *filp,
-			      struct drm_mode_fb_cmd2 *mode_cmd)
+			      struct drm_mode_fb_cmd2 *user_mode_cmd)
 {
 	struct drm_i915_gem_object *obj;
+	struct drm_mode_fb_cmd2 mode_cmd = *user_mode_cmd;
 
 	obj = to_intel_bo(drm_gem_object_lookup(dev, filp,
-						mode_cmd->handles[0]));
+						mode_cmd.handles[0]));
 	if (&obj->base == NULL)
 		return ERR_PTR(-ENOENT);
 
-	return intel_framebuffer_create(dev, mode_cmd, obj);
+	return intel_framebuffer_create(dev, &mode_cmd, obj);
 }
 
 #ifndef CONFIG_DRM_I915_FBDEV
-- 
1.9.1