linux-hardening - [PATCH v13 7/9] drm/i915: Check if the size is too big while creating shmem file

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Date:   Wed, 28 Sep 2022 11:12:58 +0300
From:   Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>
To:     intel-gfx@...ts.freedesktop.org
Cc:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        mchehab@...nel.org, chris@...is-wilson.co.uk,
        matthew.auld@...el.com, thomas.hellstrom@...ux.intel.com,
        jani.nikula@...el.com, nirmoy.das@...el.com, airlied@...hat.com,
        daniel@...ll.ch, andi.shyti@...ux.intel.com,
        andrzej.hajda@...el.com, keescook@...omium.org,
        mauro.chehab@...ux.intel.com, linux@...musvillemoes.dk,
        vitor@...saru.org, dlatypov@...gle.com, ndesaulniers@...gle.com,
        trix@...hat.com, llvm@...ts.linux.dev,
        linux-hardening@...r.kernel.org, linux-sparse@...r.kernel.org,
        nathan@...nel.org, gustavoars@...nel.org,
        luc.vanoostenryck@...il.com
Subject: [PATCH v13 7/9] drm/i915: Check if the size is too big while creating shmem file

The __shmem_file_setup() function returns -EINVAL if size is greater than
MAX_LFS_FILESIZE. To handle the same error as other code that returns
-E2BIG when the size is too large, it add a code that returns -E2BIG when
the size is larger than the size that can be handled.

v4: If BITS_PER_LONG is 32, size > MAX_LFS_FILESIZE is always false, so it
    checks only when BITS_PER_LONG is 64.

Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>
Cc: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@...el.com>
Cc: Thomas Hellström <thomas.hellstrom@...ux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@...el.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@...nel.org>
Reported-by: kernel test robot <lkp@...el.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@...el.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index 339b0a9cf2d0..ca30060e34ab 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -541,6 +541,20 @@ static int __create_shmem(struct drm_i915_private *i915,
 
 	drm_gem_private_object_init(&i915->drm, obj, size);
 
+	/* XXX: The __shmem_file_setup() function returns -EINVAL if size is
+	 * greater than MAX_LFS_FILESIZE.
+	 * To handle the same error as other code that returns -E2BIG when
+	 * the size is too large, we add a code that returns -E2BIG when the
+	 * size is larger than the size that can be handled.
+	 * If BITS_PER_LONG is 32, size > MAX_LFS_FILESIZE is always false,
+	 * so we only needs to check when BITS_PER_LONG is 64.
+	 * If BITS_PER_LONG is 32, E2BIG checks are processed when
+	 * i915_gem_object_size_2big() is called before init_object() callback
+	 * is called.
+	 */
+	if (BITS_PER_LONG == 64 && size > MAX_LFS_FILESIZE)
+		return -E2BIG;
+
 	if (i915->mm.gemfs)
 		filp = shmem_file_setup_with_mnt(i915->mm.gemfs, "i915", size,
 						 flags);
-- 
2.37.1