From 3f6e963305d4ea8f37cdbc614e7a23466ef24013 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 24 Feb 2020 10:36:52 -0600 Subject: [PATCH] netronome: 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/netronome/nfp/bpf/fw.h | 6 +++--- drivers/net/ethernet/netronome/nfp/flower/cmsg.h | 4 ++-- drivers/net/ethernet/netronome/nfp/nfp_main.h | 2 +- drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c | 8 ++++---- drivers/net/ethernet/netronome/nfp/nfp_net_repr.h | 2 +- drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h | 2 +- 6 files changed, 12 insertions(+), 12 deletions(-) diff --git a/drivers/net/ethernet/netronome/nfp/bpf/fw.h b/drivers/net/ethernet/netronome/nfp/bpf/fw.h index a83a0ad5e27d..4268a7e0f344 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/fw.h +++ b/drivers/net/ethernet/netronome/nfp/bpf/fw.h @@ -104,14 +104,14 @@ struct cmsg_req_map_op { __be32 tid; __be32 count; __be32 flags; - u8 data[0]; + u8 data[]; }; struct cmsg_reply_map_op { struct cmsg_reply_map_simple reply_hdr; __be32 count; __be32 resv; - u8 data[0]; + u8 data[]; }; struct cmsg_bpf_event { @@ -120,6 +120,6 @@ struct cmsg_bpf_event { __be64 map_ptr; __be32 data_size; __be32 pkt_size; - u8 data[0]; + u8 data[]; }; #endif diff --git a/drivers/net/ethernet/netronome/nfp/flower/cmsg.h b/drivers/net/ethernet/netronome/nfp/flower/cmsg.h index 9b50d76bbc09..bf516285510f 100644 --- a/drivers/net/ethernet/netronome/nfp/flower/cmsg.h +++ b/drivers/net/ethernet/netronome/nfp/flower/cmsg.h @@ -587,7 +587,7 @@ struct nfp_flower_cmsg_mac_repr { u8 info; u8 nbi_port; u8 phys_port; - } ports[0]; + } ports[]; }; #define NFP_FLOWER_CMSG_MAC_REPR_NBI GENMASK(1, 0) @@ -619,7 +619,7 @@ struct nfp_flower_cmsg_merge_hint { struct { __be32 host_ctx; __be64 host_cookie; - } __packed flow[0]; + } __packed flow[]; }; enum nfp_flower_cmsg_port_type { diff --git a/drivers/net/ethernet/netronome/nfp/nfp_main.h b/drivers/net/ethernet/netronome/nfp/nfp_main.h index 5d5812fd9317..fa6b13a05941 100644 --- a/drivers/net/ethernet/netronome/nfp/nfp_main.h +++ b/drivers/net/ethernet/netronome/nfp/nfp_main.h @@ -42,7 +42,7 @@ struct nfp_shared_buf; */ struct nfp_dumpspec { u32 size; - u8 data[0]; + u8 data[]; }; /** diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c b/drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c index 769ceef09756..a614df095b08 100644 --- a/drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c @@ -36,7 +36,7 @@ enum nfp_dumpspec_type { struct nfp_dump_tl { __be32 type; __be32 length; /* chunk length to follow, aligned to 8 bytes */ - char data[0]; + char data[]; }; /* NFP CPP parameters */ @@ -62,7 +62,7 @@ struct nfp_dumpspec_csr { struct nfp_dumpspec_rtsym { struct nfp_dump_tl tl; - char rtsym[0]; + char rtsym[]; }; /* header for register dumpable */ @@ -79,7 +79,7 @@ struct nfp_dump_rtsym { struct nfp_dump_common_cpp cpp; __be32 error; /* error code encountered while reading */ u8 padded_name_length; /* pad so data starts at 8 byte boundary */ - char rtsym[0]; + char rtsym[]; /* after padded_name_length, there is dump_length data */ }; @@ -92,7 +92,7 @@ struct nfp_dump_error { struct nfp_dump_tl tl; __be32 error; char padding[4]; - char spec[0]; + char spec[]; }; /* to track state through debug size calculation TLV traversal */ diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h index e0f13dfe1f39..48a74accbbd3 100644 --- a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.h @@ -18,7 +18,7 @@ struct nfp_port; */ struct nfp_reprs { unsigned int num_reprs; - struct net_device __rcu *reprs[0]; + struct net_device __rcu *reprs[]; }; /** diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h index 1531c1870020..f5360bae6f75 100644 --- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h +++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h @@ -183,7 +183,7 @@ struct nfp_eth_table { bool is_split; unsigned int fec_modes_supported; - } ports[0]; + } ports[]; }; struct nfp_eth_table *nfp_eth_read_ports(struct nfp_cpp *cpp);