Re: [PATCH v2 2/5] treewide: Replace open-coded flex arrays in unions
From: Kees Cook <hidden>
Date: 2021-08-27 16:17:46
Also in:
bpf, linux-can, linux-crypto, linux-hardening, linux-scsi, lkml, netdev
Subsystem:
can network drivers, the rest · Maintainers:
Marc Kleine-Budde, Vincent Mailhol, Linus Torvalds
On Thu, Aug 26, 2021 at 08:24:52AM +0200, Marc Kleine-Budde wrote:
[...] BTW: Is there opportunity for conversion, too? | drivers/net/can/peak_canfd/peak_pciefd_main.c:146:32: warning: array of flexible structures
Untested potential solution:
diff --git a/drivers/net/can/peak_canfd/peak_pciefd_main.c b/drivers/net/can/peak_canfd/peak_pciefd_main.c
index 1df3c4b54f03..efa2b5a52bd7 100644
--- a/drivers/net/can/peak_canfd/peak_pciefd_main.c
+++ b/drivers/net/can/peak_canfd/peak_pciefd_main.c@@ -143,7 +143,11 @@ struct pciefd_rx_dma { __le32 irq_status; __le32 sys_time_low; __le32 sys_time_high; - struct pucan_rx_msg msg[]; + /* + * with "msg" being pciefd_irq_rx_cnt(priv->irq_status)-many + * variable-sized struct pucan_rx_msg following. + */ + __le32 msg[]; } __packed __aligned(4); /* Tx Link record */
@@ -327,7 +331,7 @@ static irqreturn_t pciefd_irq_handler(int irq, void *arg) /* handle rx messages (if any) */ peak_canfd_handle_msgs_list(&priv->ucan, - rx_dma->msg, + (struct pucan_rx_msg *)rx_dma->msg, pciefd_irq_rx_cnt(priv->irq_status)); /* handle tx link interrupt (if any) */
It's not great, but it's also not strictly a flex array, in the sense that since struct pucan_rx_msg is a variable size, the compiler cannot reason about the size of struct pciefd_rx_dma based only on the irq_status encoding... -- Kees Cook