6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Arinzon <darinzon@xxxxxxxxxx> [ Upstream commit 713a85195aad25d8a26786a37b674e3e5ec09e3c ] Small unsigned types are promoted to larger signed types in the case of multiplication, the result of which may overflow. In case the result of such a multiplication has its MSB turned on, it will be sign extended with '1's. This changes the multiplication result. Code example of the phenomenon: ------------------------------- u16 x, y; size_t z1, z2; x = y = 0xffff; printk("x=%x y=%x\n",x,y); z1 = x*y; z2 = (size_t)x*y; printk("z1=%lx z2=%lx\n", z1, z2); Output: ------- x=ffff y=ffff z1=fffffffffffe0001 z2=fffe0001 The expected result of ffff*ffff is fffe0001, and without the explicit casting to avoid the unwanted sign extension we got fffffffffffe0001. This commit adds an explicit casting to avoid the sign extension issue. Fixes: 689b2bdaaa14 ("net: ena: add functions for handling Low Latency Queues in ena_com") Signed-off-by: Arthur Kiyanovski <akiyano@xxxxxxxxxx> Signed-off-by: David Arinzon <darinzon@xxxxxxxxxx> Reviewed-by: Shannon Nelson <shannon.nelson@xxxxxxx> Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/net/ethernet/amazon/ena/ena_com.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c index 633b321d7fdd9..4db689372980e 100644 --- a/drivers/net/ethernet/amazon/ena/ena_com.c +++ b/drivers/net/ethernet/amazon/ena/ena_com.c @@ -362,7 +362,7 @@ static int ena_com_init_io_sq(struct ena_com_dev *ena_dev, ENA_COM_BOUNCE_BUFFER_CNTRL_CNT; io_sq->bounce_buf_ctrl.next_to_use = 0; - size = io_sq->bounce_buf_ctrl.buffer_size * + size = (size_t)io_sq->bounce_buf_ctrl.buffer_size * io_sq->bounce_buf_ctrl.buffers_num; dev_node = dev_to_node(ena_dev->dmadev); -- 2.43.0