rsxx: Use struct_size() in vmalloc()

Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows
that, in the worst scenario, could lead to heap overflows.

This code was detected with the help of Coccinelle and, audited and
fixed manually.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20210513203730.GA212128@embeddedor
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/rsxx/dma.c b/drivers/block/rsxx/dma.c
index 0574f44..ed182f3 100644 (file)
--- a/drivers/block/rsxx/dma.c
+++ b/drivers/block/rsxx/dma.c
@@ -74,9 +74,6 @@ struct dma_tracker {
        struct rsxx_dma *dma;
 };
 
-#define DMA_TRACKER_LIST_SIZE8 (sizeof(struct dma_tracker_list) + \
-               (sizeof(struct dma_tracker) * RSXX_MAX_OUTSTANDING_CMDS))
-
 struct dma_tracker_list {
        spinlock_t              lock;
        int                     head;
@@ -808,7 +805,8 @@ static int rsxx_dma_ctrl_init(struct pci_dev *dev,
 
        memset(&ctrl->stats, 0, sizeof(ctrl->stats));
 
-       ctrl->trackers = vmalloc(DMA_TRACKER_LIST_SIZE8);
+       ctrl->trackers = vmalloc(struct_size(ctrl->trackers, list,
+                                            RSXX_MAX_OUTSTANDING_CMDS));
        if (!ctrl->trackers)
                return -ENOMEM;