[PATCH v11 7/9] drm/i915: Check if the size is too big while creating shmem file

Gwan-gyeong Mun
2022-09-23T08:28:26Z

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@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.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