Re: [PATCH] IB/core, cache: Replace zero-length array with flexible-array member

From: Jason Gunthorpe
Date: Thu Feb 20 2020 - 12:38:00 EST

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On Wed, Feb 12, 2020 at 07:04:25PM -0600, Gustavo A. R. Silva wrote:
> 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 <gustavo@xxxxxxxxxxxxxx>
> ---
> drivers/infiniband/core/cache.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

I squished the four drivers/infiniband patches together and added a
few more, see below. Applied to for-next

It would be fanatstic to follow this up with some analysis to find
cases where sizeof() is performed on a struct with a [] flex array -
these days people should be using struct_size() (interested DanC?)

Thanks,
Jason

diff --git a/drivers/infiniband/core/mad_priv.h b/drivers/infiniband/core/mad_priv.h
index 956b3a7dfed7ed..403d8673a2f9ea 100644
--- a/drivers/infiniband/core/mad_priv.h
+++ b/drivers/infiniband/core/mad_priv.h
@@ -79,13 +79,13 @@ struct ib_mad_private {
struct ib_mad_private_header header;
size_t mad_size;
struct ib_grh grh;
- u8 mad[0];
+ u8 mad[];
} __packed;

struct ib_rmpp_segment {
struct list_head list;
u32 num;
- u8 data[0];
+ u8 data[];
};

struct ib_mad_agent_private {
diff --git a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
index 7d06b0f8d49a00..e8e11bd95e4296 100644
--- a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
+++ b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
@@ -707,7 +707,7 @@ struct mpa_message {
u8 flags;
u8 revision;
__be16 private_data_size;
- u8 private_data[0];
+ u8 private_data[];
};

struct mpa_v2_conn_params {
@@ -719,7 +719,7 @@ struct terminate_message {
u8 layer_etype;
u8 ecode;
__be16 hdrct_rsvd;
- u8 len_hdrs[0];
+ u8 len_hdrs[];
};

#define TERM_MAX_LENGTH (sizeof(struct terminate_message) + 2 + 18 + 28)
diff --git a/drivers/infiniband/hw/cxgb4/t4fw_ri_api.h b/drivers/infiniband/hw/cxgb4/t4fw_ri_api.h
index cbdb300a47943a..a2f5e29ef2264d 100644
--- a/drivers/infiniband/hw/cxgb4/t4fw_ri_api.h
+++ b/drivers/infiniband/hw/cxgb4/t4fw_ri_api.h
@@ -123,7 +123,7 @@ struct fw_ri_dsgl {
__be32 len0;
__be64 addr0;
#ifndef C99_NOT_SUPPORTED
- struct fw_ri_dsge_pair sge[0];
+ struct fw_ri_dsge_pair sge[];
#endif
};

@@ -139,7 +139,7 @@ struct fw_ri_isgl {
__be16 nsge;
__be32 r2;
#ifndef C99_NOT_SUPPORTED
- struct fw_ri_sge sge[0];
+ struct fw_ri_sge sge[];
#endif
};

@@ -149,7 +149,7 @@ struct fw_ri_immd {
__be16 r2;
__be32 immdlen;
#ifndef C99_NOT_SUPPORTED
- __u8 data[0];
+ __u8 data[];
#endif
};

@@ -321,7 +321,7 @@ struct fw_ri_res_wr {
__be32 len16_pkd;
__u64 cookie;
#ifndef C99_NOT_SUPPORTED
- struct fw_ri_res res[0];
+ struct fw_ri_res res[];
#endif
};

diff --git a/drivers/infiniband/hw/hfi1/mad.c b/drivers/infiniband/hw/hfi1/mad.c
index a51bcd2b439128..7073f237a94938 100644
--- a/drivers/infiniband/hw/hfi1/mad.c
+++ b/drivers/infiniband/hw/hfi1/mad.c
@@ -2381,7 +2381,7 @@ struct opa_port_status_rsp {
__be64 port_vl_rcv_bubble;
__be64 port_vl_mark_fecn;
__be64 port_vl_xmit_discards;
- } vls[0]; /* real array size defined by # bits set in vl_select_mask */
+ } vls[]; /* real array size defined by # bits set in vl_select_mask */
};

enum counter_selects {
@@ -2423,7 +2423,7 @@ struct opa_aggregate {
__be16 attr_id;
__be16 err_reqlength; /* 1 bit, 8 res, 7 bit */
__be32 attr_mod;
- u8 data[0];
+ u8 data[];
};

#define MSK_LLI 0x000000f0
diff --git a/drivers/infiniband/hw/hfi1/mad.h b/drivers/infiniband/hw/hfi1/mad.h
index 2f48e69536290c..889e63d3f2ccd0 100644
--- a/drivers/infiniband/hw/hfi1/mad.h
+++ b/drivers/infiniband/hw/hfi1/mad.h
@@ -165,7 +165,7 @@ struct opa_mad_notice_attr {
} __packed ntc_2048;

};
- u8 class_data[0];
+ u8 class_data[];
};

#define IB_VLARB_LOWPRI_0_31 1
diff --git a/drivers/infiniband/hw/hfi1/pio.h b/drivers/infiniband/hw/hfi1/pio.h
index c9a58b642bdd6f..0102262343c0f6 100644
--- a/drivers/infiniband/hw/hfi1/pio.h
+++ b/drivers/infiniband/hw/hfi1/pio.h
@@ -243,7 +243,7 @@ struct sc_config_sizes {
*/
struct pio_map_elem {
u32 mask;
- struct send_context *ksc[0];
+ struct send_context *ksc[];
};

/*
@@ -263,7 +263,7 @@ struct pio_vl_map {
u32 mask;
u8 actual_vls;
u8 vls;
- struct pio_map_elem *map[0];
+ struct pio_map_elem *map[];
};

int pio_map_init(struct hfi1_devdata *dd, u8 port, u8 num_vls,
diff --git a/drivers/infiniband/hw/hfi1/sdma.c b/drivers/infiniband/hw/hfi1/sdma.c
index a51525647ac86b..c93ea021cf4939 100644
--- a/drivers/infiniband/hw/hfi1/sdma.c
+++ b/drivers/infiniband/hw/hfi1/sdma.c
@@ -833,7 +833,7 @@ struct sdma_engine *sdma_select_engine_sc(
struct sdma_rht_map_elem {
u32 mask;
u8 ctr;
- struct sdma_engine *sde[0];
+ struct sdma_engine *sde[];
};

struct sdma_rht_node {
diff --git a/drivers/infiniband/hw/hfi1/sdma.h b/drivers/infiniband/hw/hfi1/sdma.h
index 1e2e40f79cb205..7a851191f9870f 100644
--- a/drivers/infiniband/hw/hfi1/sdma.h
+++ b/drivers/infiniband/hw/hfi1/sdma.h
@@ -1002,7 +1002,7 @@ void sdma_engine_interrupt(struct sdma_engine *sde, u64 status);
*/
struct sdma_map_elem {
u32 mask;
- struct sdma_engine *sde[0];
+ struct sdma_engine *sde[];
};

/**
@@ -1024,7 +1024,7 @@ struct sdma_vl_map {
u32 mask;
u8 actual_vls;
u8 vls;
- struct sdma_map_elem *map[0];
+ struct sdma_map_elem *map[];
};

int sdma_map_init(
diff --git a/drivers/infiniband/hw/hfi1/user_exp_rcv.h b/drivers/infiniband/hw/hfi1/user_exp_rcv.h
index 6257eee083a1a3..332abb446861a9 100644
--- a/drivers/infiniband/hw/hfi1/user_exp_rcv.h
+++ b/drivers/infiniband/hw/hfi1/user_exp_rcv.h
@@ -73,7 +73,7 @@ struct tid_rb_node {
dma_addr_t dma_addr;
bool freed;
unsigned int npages;
- struct page *pages[0];
+ struct page *pages[];
};

static inline int num_user_pages(unsigned long addr,
diff --git a/drivers/infiniband/hw/i40iw/i40iw_cm.h b/drivers/infiniband/hw/i40iw/i40iw_cm.h
index 66dc1ba0338900..6e43e4d730f4c4 100644
--- a/drivers/infiniband/hw/i40iw/i40iw_cm.h
+++ b/drivers/infiniband/hw/i40iw/i40iw_cm.h
@@ -85,7 +85,7 @@ struct ietf_mpa_v1 {
u8 flags;
u8 rev;
__be16 priv_data_len;
- u8 priv_data[0];
+ u8 priv_data[];
};

#define ietf_mpa_req_resp_frame ietf_mpa_frame
@@ -101,7 +101,7 @@ struct ietf_mpa_v2 {
u8 rev;
__be16 priv_data_len;
struct ietf_rtr_msg rtr_msg;
- u8 priv_data[0];
+ u8 priv_data[];
};

struct i40iw_cm_node;
diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.h b/drivers/infiniband/hw/mthca/mthca_memfree.h
index da9b8f9b884f3a..f9a2e65e2ff59a 100644
--- a/drivers/infiniband/hw/mthca/mthca_memfree.h
+++ b/drivers/infiniband/hw/mthca/mthca_memfree.h
@@ -68,7 +68,7 @@ struct mthca_icm_table {
int lowmem;
int coherent;
struct mutex mutex;
- struct mthca_icm *icm[0];
+ struct mthca_icm *icm[];
};

struct mthca_icm_iter {
diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.h b/drivers/infiniband/hw/usnic/usnic_uiom.h
index 70be49b1ca0528..7ec8991ace673e 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom.h
+++ b/drivers/infiniband/hw/usnic/usnic_uiom.h
@@ -77,7 +77,7 @@ struct usnic_uiom_reg {
struct usnic_uiom_chunk {
struct list_head list;
int nents;
- struct scatterlist page_list[0];
+ struct scatterlist page_list[];
};

struct usnic_uiom_pd *usnic_uiom_alloc_pd(void);
diff --git a/drivers/infiniband/sw/rxe/rxe_queue.h b/drivers/infiniband/sw/rxe/rxe_queue.h
index acd0a925481c95..8ef17d61702214 100644
--- a/drivers/infiniband/sw/rxe/rxe_queue.h
+++ b/drivers/infiniband/sw/rxe/rxe_queue.h
@@ -63,7 +63,7 @@ struct rxe_queue_buf {
__u32 pad_2[31];
__u32 consumer_index;
__u32 pad_3[31];
- __u8 data[0];
+ __u8 data[];
};

struct rxe_queue {
diff --git a/drivers/infiniband/ulp/opa_vnic/opa_vnic_encap.h b/drivers/infiniband/ulp/opa_vnic/opa_vnic_encap.h
index 4480092c68e097..0b3570dc606d24 100644
--- a/drivers/infiniband/ulp/opa_vnic/opa_vnic_encap.h
+++ b/drivers/infiniband/ulp/opa_vnic/opa_vnic_encap.h
@@ -258,7 +258,7 @@ struct opa_veswport_mactable {
__be16 offset;
__be16 num_entries;
__be32 mac_tbl_digest;
- struct opa_veswport_mactable_entry tbl_entries[0];
+ struct opa_veswport_mactable_entry tbl_entries[];
} __packed;

/**
@@ -440,7 +440,7 @@ struct opa_veswport_iface_macs {
__be16 num_macs_in_msg;
__be16 tot_macs_in_lst;
__be16 gen_count;
- struct opa_vnic_iface_mac_entry entry[0];
+ struct opa_vnic_iface_mac_entry entry[];
} __packed;

/**
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index 5359ece561cad8..6fabcc2faf1f08 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -309,7 +309,7 @@ struct srp_fr_pool {
int max_page_list_len;
spinlock_t lock;
struct list_head free_list;
- struct srp_fr_desc desc[0];
+ struct srp_fr_desc desc[];
};

/**
diff --git a/include/rdma/ib_fmr_pool.h b/include/rdma/ib_fmr_pool.h
index f8982e4e9702ad..2fd9bfb6d648cc 100644
--- a/include/rdma/ib_fmr_pool.h
+++ b/include/rdma/ib_fmr_pool.h
@@ -73,7 +73,7 @@ struct ib_pool_fmr {
int remap_count;
u64 io_virtual_address;
int page_list_len;
- u64 page_list[0];
+ u64 page_list[];
};

struct ib_fmr_pool *ib_create_fmr_pool(struct ib_pd *pd,
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 5f3a04ead9f593..bbc5cfb57cd2bb 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -1876,7 +1876,7 @@ struct ib_flow_eth_filter {
__be16 ether_type;
__be16 vlan_tag;
/* Must be last */
- u8 real_sz[0];
+ u8 real_sz[];
};

struct ib_flow_spec_eth {
@@ -1890,7 +1890,7 @@ struct ib_flow_ib_filter {
__be16 dlid;
__u8 sl;
/* Must be last */
- u8 real_sz[0];
+ u8 real_sz[];
};

struct ib_flow_spec_ib {
@@ -1915,7 +1915,7 @@ struct ib_flow_ipv4_filter {
u8 ttl;
u8 flags;
/* Must be last */
- u8 real_sz[0];
+ u8 real_sz[];
};

struct ib_flow_spec_ipv4 {
@@ -1933,7 +1933,7 @@ struct ib_flow_ipv6_filter {
u8 traffic_class;
u8 hop_limit;
/* Must be last */
- u8 real_sz[0];
+ u8 real_sz[];
};

struct ib_flow_spec_ipv6 {
@@ -1947,7 +1947,7 @@ struct ib_flow_tcp_udp_filter {
__be16 dst_port;
__be16 src_port;
/* Must be last */
- u8 real_sz[0];
+ u8 real_sz[];
};

struct ib_flow_spec_tcp_udp {
@@ -1959,7 +1959,7 @@ struct ib_flow_spec_tcp_udp {

struct ib_flow_tunnel_filter {
__be32 tunnel_id;
- u8 real_sz[0];
+ u8 real_sz[];
};

/* ib_flow_spec_tunnel describes the Vxlan tunnel
@@ -1976,7 +1976,7 @@ struct ib_flow_esp_filter {
__be32 spi;
__be32 seq;
/* Must be last */
- u8 real_sz[0];
+ u8 real_sz[];
};

struct ib_flow_spec_esp {
@@ -1991,7 +1991,7 @@ struct ib_flow_gre_filter {
__be16 protocol;
__be32 key;
/* Must be last */
- u8 real_sz[0];
+ u8 real_sz[];
};

struct ib_flow_spec_gre {
@@ -2004,7 +2004,7 @@ struct ib_flow_spec_gre {
struct ib_flow_mpls_filter {
__be32 tag;
/* Must be last */
- u8 real_sz[0];
+ u8 real_sz[];
};

struct ib_flow_spec_mpls {
diff --git a/include/rdma/opa_vnic.h b/include/rdma/opa_vnic.h
index 0c07a70bd7f61d..e90b149fe92a0b 100644
--- a/include/rdma/opa_vnic.h
+++ b/include/rdma/opa_vnic.h
@@ -75,7 +75,7 @@
struct opa_vnic_rdma_netdev {
struct rdma_netdev rn; /* keep this first */
/* followed by device private data */
- char *dev_priv[0];
+ char *dev_priv[];
};

static inline void *opa_vnic_priv(const struct net_device *dev)
diff --git a/include/rdma/rdmavt_mr.h b/include/rdma/rdmavt_mr.h
index 72a3856d4057f5..ce6c888f7fe754 100644
--- a/include/rdma/rdmavt_mr.h
+++ b/include/rdma/rdmavt_mr.h
@@ -85,7 +85,7 @@ struct rvt_mregion {
u8 lkey_published; /* in global table */
struct percpu_ref refcount;
struct completion comp; /* complete when refcount goes to zero */
- struct rvt_segarray *map[0]; /* the segments */
+ struct rvt_segarray *map[]; /* the segments */
};

#define RVT_MAX_LKEY_TABLE_BITS 23
diff --git a/include/rdma/rdmavt_qp.h b/include/rdma/rdmavt_qp.h
index 0d5c70e2d8ab33..5fc10108703a43 100644
--- a/include/rdma/rdmavt_qp.h
+++ b/include/rdma/rdmavt_qp.h
@@ -191,7 +191,7 @@ struct rvt_swqe {
u32 ssn; /* send sequence number */
u32 length; /* total length of data in sg_list */
void *priv; /* driver dependent field */
- struct rvt_sge sg_list[0];
+ struct rvt_sge sg_list[];
};

/**

Next message: Andrew F. Davis: "Re: omap-secure.c:undefined reference to `__arm_smccc_smc'"
Previous message: Orson Zhai: "[PATCH] Revert "PM / devfreq: Modify the device name as devfreq(X) for sysfs""
Next in thread: Gustavo A. R. Silva: "Re: [PATCH] IB/core, cache: Replace zero-length array with flexible-array member"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]