From d1c73cbdf9d3f6181a50398568372ef41b1f485c Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 24 Feb 2020 18:18:26 -0600 Subject: [PATCH] net: cisco: 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] Lastly, fix the following checkpatch warning: CHECK: Prefer kernel type 'u32' over 'u_int32_t' #61: FILE: drivers/net/ethernet/cisco/enic/vnic_devcmd.h:653: + u_int32_t val[]; 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/cisco/enic/vnic_devcmd.h | 8 ++++---- drivers/net/ethernet/cisco/enic/vnic_vic.h | 2 +- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/cisco/enic/vnic_devcmd.h b/drivers/net/ethernet/cisco/enic/vnic_devcmd.h index fef5a0a0663d..fcc4a3ccdd94 100644 --- a/drivers/net/ethernet/cisco/enic/vnic_devcmd.h +++ b/drivers/net/ethernet/cisco/enic/vnic_devcmd.h @@ -541,7 +541,7 @@ struct vnic_devcmd_notify { struct vnic_devcmd_provinfo { u8 oui[3]; u8 type; - u8 data[0]; + u8 data[]; }; /* These are used in flags field of different filters to denote @@ -648,9 +648,9 @@ enum { #define FILTER_MAX_BUF_SIZE 100 struct filter_tlv { - u_int32_t type; - u_int32_t length; - u_int32_t val[0]; + u32 type; + u32 length; + u32 val[]; }; enum { diff --git a/drivers/net/ethernet/cisco/enic/vnic_vic.h b/drivers/net/ethernet/cisco/enic/vnic_vic.h index 9ef81f148351..057776908828 100644 --- a/drivers/net/ethernet/cisco/enic/vnic_vic.h +++ b/drivers/net/ethernet/cisco/enic/vnic_vic.h @@ -59,7 +59,7 @@ struct vic_provinfo { u16 type; u16 length; u8 value[0]; - } tlv[0]; + } tlv[]; } __packed; #define VIC_PROVINFO_ADD_TLV(vp, tlvtype, tlvlen, data) \