linux-kernel - [PATCH 4.19 211/280] drm/i915: Relax mmap VMA check

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Date:   Fri, 22 Mar 2019 12:16:04 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Adam Zabrocki <adamza@...rosoft.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Akash Goel <akash.goel@...el.com>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        intel-gfx@...ts.freedesktop.org, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 211/280] drm/i915: Relax mmap VMA check

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

------------------

[ Upstream commit ca22f32a6296cbfa29de56328c8505560a18cfa8 ]

Legacy behaviour was to allow non-page-aligned mmap requests, as does the
linux mmap(2) implementation by virtue of automatically rounding up for
the caller.

To avoid breaking legacy userspace relax the newly introduced fix.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Fixes: 5c4604e757ba ("drm/i915: Prevent a race during I915_GEM_MMAP ioctl with WC set")
Reported-by: Guenter Roeck <linux@...ck-us.net>
Cc: Adam Zabrocki <adamza@...rosoft.com>
Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
Cc: <stable@...r.kernel.org> # v4.0+
Cc: Akash Goel <akash.goel@...el.com>
Cc: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@...ux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc: intel-gfx@...ts.freedesktop.org
Reviewed-by: Chris Wilson <chris@...is-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190305110409.28633-1-tvrtko.ursulin@linux.intel.com
(cherry picked from commit a90e1948efb648f567444f87f3c19b2a0787affd)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/i915/i915_gem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 280c851714e6..03cda197fb6b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1828,7 +1828,8 @@ __vma_matches(struct vm_area_struct *vma, struct file *filp,
 	if (vma->vm_file != filp)
 		return false;
 
-	return vma->vm_start == addr && (vma->vm_end - vma->vm_start) == size;
+	return vma->vm_start == addr &&
+	       (vma->vm_end - vma->vm_start) == PAGE_ALIGN(size);
 }
 
 /**
-- 
2.19.1