qlogic: 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 detected 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 <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/qlogic/netxen/netxen_nic.h b/drivers/net/ethernet/qlogic/netxen/netxen_nic.h
index 3dce769d83a193a38babe7b3bae16ae76722c6c5..86153660d2457c8267ed512190c98a51290b9d75 100644 (file)
--- a/drivers/net/ethernet/qlogic/netxen/netxen_nic.h
+++ b/drivers/net/ethernet/qlogic/netxen/netxen_nic.h
@@ -1316,7 +1316,7 @@ struct netxen_minidump_template_hdr {
        u32 driver_info_word4;
        u32 saved_state_array[NX_DUMP_STATE_ARRAY_LEN];
        u32 capture_size_array[NX_DUMP_CAP_SIZE_ARRAY_LEN];
-       u32 rsvd[0];
+       u32 rsvd[];
 };
 
 /* Common Entry Header:  Common to All Entry Types */

diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic.h b/drivers/net/ethernet/qlogic/qlcnic/qlcnic.h
index 374a4d4371f99f23fe9d4507e0cbd33e177fbd85..134611aa2c9a31bf1b8a54fc24ec8e7393a8f075 100644 (file)
--- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic.h
+++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic.h
@@ -418,7 +418,7 @@ struct qlcnic_83xx_dump_template_hdr {
        u32     saved_state[16];
        u32     cap_sizes[8];
        u32     ocm_wnd_reg[16];
-       u32     rsvd[0];
+       u32     rsvd[];
 };
 
 struct qlcnic_82xx_dump_template_hdr {
@@ -436,7 +436,7 @@ struct qlcnic_82xx_dump_template_hdr {
        u32     cap_sizes[8];
        u32     rsvd[7];
        u32     capabilities;
-       u32     rsvd1[0];
+       u32     rsvd1[];
 };
 
 #define QLC_PEX_DMA_READ_SIZE  (PAGE_SIZE * 16)
@@ -740,7 +740,7 @@ struct qlcnic_hostrq_rx_ctx {
           The following is packed:
           - N hostrq_rds_rings
           - N hostrq_sds_rings */
-       char data[0];
+       char data[];
 } __packed;
 
 struct qlcnic_cardrsp_rds_ring{
@@ -769,7 +769,7 @@ struct qlcnic_cardrsp_rx_ctx {
           The following is packed:
           - N cardrsp_rds_rings
           - N cardrs_sds_rings */
-       char data[0];
+       char data[];
 } __packed;
 
 #define SIZEOF_HOSTRQ_RX(HOSTRQ_RX, rds_rings, sds_rings)      \