There are some potential integer overflows here on 64 bit systems.
The condition "if (nfences > SIZE_MAX / sizeof(*fences))" can only be
true on 32 bit systems, it's a no-op on 64 bit, so let's ignore the
check for now and look a couple lines after:
if (!access_ok(VERIFY_READ, user, nfences * 2 * sizeof(u32)))
^^^^^^^^^^^
"nfences" is an unsigned int, so if we set it to UINT_MAX and multiply
by two, it's going to have an integer overflow. The multiplication by
sizeof(u32) is OK because that gets type promoted to size_t. This patch
changes the access_ok() check to use sizeof(*user) which fixes the
integer overflow and is also more readable.
The "args->buffer_count" variable is an unsigned int as well so it could
overflow if it's set to UINT_MAX when we do:
exec2_list = kvmalloc_array(args->buffer_count + 1, sz,
^^^^^^^^^^^^^^^^^^^^^^
Originally, those two integer overflow checks were against UINT_MAX
instead of SIZE_MAX and this patch changes them back.
Fixes: 2889caa92321 ("drm/i915: Eliminate lots of iterations over the execobjects array")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
v2: Use sizeof(*users)
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 15ab3e6792f9..11419b81cf13 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -2156,7 +2156,7 @@ get_fence_array(struct drm_i915_gem_execbuffer2 *args,
return ERR_PTR(-EINVAL);
user = u64_to_user_ptr(args->cliprects_ptr);
- if (!access_ok(VERIFY_READ, user, nfences * 2 * sizeof(u32)))
+ if (!access_ok(VERIFY_READ, user, nfences * sizeof(*user)))
return ERR_PTR(-EFAULT);
fences = kvmalloc_array(args->num_cliprects, sizeof(*fences),
@@ -2520,7 +2520,7 @@ i915_gem_execbuffer(struct drm_device *dev, void *data,
unsigned int i;
int err;
- if (args->buffer_count < 1 || args->buffer_count > SIZE_MAX / sz - 1) {
+ if (args->buffer_count < 1 || args->buffer_count > UINT_MAX / sz - 1) {
DRM_DEBUG("execbuf2 with %d buffers\n", args->buffer_count);
return -EINVAL;
}
@@ -2609,7 +2609,7 @@ i915_gem_execbuffer2(struct drm_device *dev, void *data,
struct drm_syncobj **fences = NULL;
int err;
- if (args->buffer_count < 1 || args->buffer_count > SIZE_MAX / sz - 1) {
+ if (args->buffer_count < 1 || args->buffer_count > UINT_MAX / sz - 1) {
DRM_DEBUG("execbuf2 with %d buffers\n", args->buffer_count);
return -EINVAL;
}
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