This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1][2].
The "struct dma_fence_array" can be refactored to add a flex array in order
to have the "callback structures allocated behind the array" be more
explicit.
Do so:
- makes the code more readable and safer.
- allows using __counted_by() for additional checks
- avoids some pointer arithmetic in dma_fence_array_enable_signaling()
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
Link: https://github.com/KSPP/linux/issues/160 [2]
Signed-off-by: Christophe JAILLET <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
---
Compile tested only.
Changes in v2:
- Name the new field 'callbacks' instead of 'cb' [Christian König]
v1: https://lore.kernel.org/all/d3204a5b4776553455c2cfb1def72f1dae0dba25.1716054403.git.christophe.jaillet@wanadoo.fr/
---
drivers/dma-buf/dma-fence-array.c | 10 ++++------
include/linux/dma-fence-array.h | 3 +++
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
index 9b3ce8948351..c74ac197d5fe 100644
--- a/drivers/dma-buf/dma-fence-array.c
+++ b/drivers/dma-buf/dma-fence-array.c
@@ -70,7 +70,7 @@ static void dma_fence_array_cb_func(struct dma_fence *f,
static bool dma_fence_array_enable_signaling(struct dma_fence *fence)
{
struct dma_fence_array *array = to_dma_fence_array(fence);
- struct dma_fence_array_cb *cb = (void *)(&array[1]);
+ struct dma_fence_array_cb *cb = array->callbacks;
unsigned i;
for (i = 0; i < array->num_fences; ++i) {
@@ -168,22 +168,20 @@ struct dma_fence_array *dma_fence_array_create(int num_fences,
bool signal_on_any)
{
struct dma_fence_array *array;
- size_t size = sizeof(*array);
WARN_ON(!num_fences || !fences);
- /* Allocate the callback structures behind the array. */
- size += num_fences * sizeof(struct dma_fence_array_cb);
- array = kzalloc(size, GFP_KERNEL);
+ array = kzalloc(struct_size(array, callbacks, num_fences), GFP_KERNEL);
if (!array)
return NULL;
+ array->num_fences = num_fences;
+
spin_lock_init(&array->lock);
dma_fence_init(&array->base, &dma_fence_array_ops, &array->lock,
context, seqno);
init_irq_work(&array->work, irq_dma_fence_array_work);
- array->num_fences = num_fences;
atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
array->fences = fences;
diff --git a/include/linux/dma-fence-array.h b/include/linux/dma-fence-array.h
index ec7f25def392..29c5650c1038 100644
--- a/include/linux/dma-fence-array.h
+++ b/include/linux/dma-fence-array.h
@@ -33,6 +33,7 @@ struct dma_fence_array_cb {
* @num_pending: fences in the array still pending
* @fences: array of the fences
* @work: internal irq_work function
+ * @callbacks: array of callback helpers
*/
struct dma_fence_array {
struct dma_fence base;
@@ -43,6 +44,8 @@ struct dma_fence_array {
struct dma_fence **fences;
struct irq_work work;
+
+ struct dma_fence_array_cb callbacks[] __counted_by(num_fences);
};
/**
--
2.45.1