From cc5b48b567a2f668d6f301cb0dd08d65ff1f7fa2 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 24 Feb 2020 10:43:46 -0600 Subject: [PATCH] freescale: Replace zero-length array with flexible-array member The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller --- drivers/net/ethernet/freescale/enetc/enetc.h | 2 +- drivers/net/ethernet/freescale/enetc/enetc_hw.h | 2 +- drivers/net/ethernet/freescale/fec.h | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/freescale/enetc/enetc.h b/drivers/net/ethernet/freescale/enetc/enetc.h index dd4a227..9938f7a 100644 --- a/drivers/net/ethernet/freescale/enetc/enetc.h +++ b/drivers/net/ethernet/freescale/enetc/enetc.h @@ -163,7 +163,7 @@ struct enetc_int_vector { char name[ENETC_INT_NAME_MAX]; struct enetc_bdr rx_ring ____cacheline_aligned_in_smp; - struct enetc_bdr tx_ring[0]; + struct enetc_bdr tx_ring[]; }; struct enetc_cls_rule { diff --git a/drivers/net/ethernet/freescale/enetc/enetc_hw.h b/drivers/net/ethernet/freescale/enetc/enetc_hw.h index 62554f2..da134e2 100644 --- a/drivers/net/ethernet/freescale/enetc/enetc_hw.h +++ b/drivers/net/ethernet/freescale/enetc/enetc_hw.h @@ -588,7 +588,7 @@ struct tgs_gcl_data { __le32 bth; __le32 ct; __le32 cte; - struct gce entry[0]; + struct gce entry[]; }; struct enetc_cbd { diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h index f79e57f..bd898f5 100644 --- a/drivers/net/ethernet/freescale/fec.h +++ b/drivers/net/ethernet/freescale/fec.h @@ -584,7 +584,7 @@ struct fec_enet_private { int pps_enable; unsigned int next_counter; - u64 ethtool_stats[0]; + u64 ethtool_stats[]; }; void fec_ptp_init(struct platform_device *pdev, int irq_idx); -- 2.7.4