Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Message-Id: <ebf1250b6d4f351469fb339e5399d8b92aa8a1c1.1585898438.git.christophe.leroy@c-s.fr>
In-Reply-To: <36e43241c7f043a24b5069e78c6a7edd11043be5.1585898438.git.christophe.leroy@c-s.fr>
References: <36e43241c7f043a24b5069e78c6a7edd11043be5.1585898438.git.christophe.leroy@c-s.fr>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Subject: [PATCH v2 3/5] drm/i915/gem: Replace user_access_begin by
 user_write_access_begin
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, airlied@linux.ie,
        daniel@ffwll.ch, torvalds@linux-foundation.org,
        viro@zeniv.linux.org.uk, akpm@linux-foundation.org,
        keescook@chromium.org, hpa@zytor.com
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-mm@kvack.org, linux-arch@vger.kernel.org,
        intel-gfx@lists.freedesktop.org
Date:   Fri,  3 Apr 2020 07:20:52 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When i915_gem_execbuffer2_ioctl() is using user_access_begin(),
that's only to perform unsafe_put_user() so use
user_write_access_begin() in order to only open write access.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
v2: Rebased (one part of the patch flies away)
---
 drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 36d069504836..b4c903308590 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -2794,7 +2794,8 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
 		 * And this range already got effectively checked earlier
 		 * when we did the "copy_from_user()" above.
 		 */
-		if (!user_access_begin(user_exec_list, count * sizeof(*user_exec_list)))
+		if (!user_write_access_begin(user_exec_list,
+					     count * sizeof(*user_exec_list)))
 			goto end;
 
 		for (i = 0; i < args->buffer_count; i++) {
@@ -2808,7 +2809,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
 					end_user);
 		}
 end_user:
-		user_access_end();
+		user_write_access_end();
 end:;
 	}
 
-- 
2.25.0