phonet: fix building with clang [Linux 5.0]

This Linux kernel change "phonet: fix building with clang" is included in the Linux 5.0 release. This change is authored by Arnd Bergmann <arnd [at] arndb.de> on Tue Feb 19 22:53:50 2019 +0100. The commit for this change in Linux stable tree is 6321aa1 (patch).

phonet: fix building with clang

clang warns about overflowing the data[] member in the struct pnpipehdr:

net/phonet/pep.c:295:8: warning: array index 4 is past the end of the array (which contains 1 element) [-Warray-bounds]
                        if (hdr->data[4] == PEP_IND_READY)
                            ^         ~
include/net/phonet/pep.h:66:3: note: array 'data' declared here
                u8              data[1];

Using a flexible array member at the end of the struct avoids the
warning, but since we cannot have a flexible array member inside
of the union, each index now has to be moved back by one, which
makes it a little uglier.

Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: RĂ©mi Denis-Courmont <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

There are 37 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 include/net/phonet/pep.h |  5 +++--
 net/phonet/pep.c         | 32 ++++++++++++++++----------------
 2 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/include/net/phonet/pep.h b/include/net/phonet/pep.h
index b669fe6d..98f31c7 100644
--- a/include/net/phonet/pep.h
+++ b/include/net/phonet/pep.h
@@ -63,10 +63,11 @@ struct pnpipehdr {
        u8      state_after_reset;  /* reset request */
        u8      error_code;     /* any response */
        u8      pep_type;       /* status indication */
-       u8      data[1];
+       u8      data0;          /* anything else */
    };
+   u8          data[];
 };
-#define other_pep_type     data[1]
+#define other_pep_type     data[0]

 static inline struct pnpipehdr *pnp_hdr(struct sk_buff *skb)
 {
diff --git a/net/phonet/pep.c b/net/phonet/pep.c
index 9fc76b1..db34735 100644
--- a/net/phonet/pep.c
+++ b/net/phonet/pep.c
@@ -132,7 +132,7 @@ static int pep_indicate(struct sock *sk, u8 id, u8 code,
    ph->utid = 0;
    ph->message_id = id;
    ph->pipe_handle = pn->pipe_handle;
-   ph->data[0] = code;
+   ph->error_code = code;
    return pn_skb_send(sk, skb, NULL);
 }

@@ -153,7 +153,7 @@ static int pipe_handler_request(struct sock *sk, u8 id, u8 code,
    ph->utid = id; /* whatever */
    ph->message_id = id;
    ph->pipe_handle = pn->pipe_handle;
-   ph->data[0] = code;
+   ph->error_code = code;
    return pn_skb_send(sk, skb, NULL);
 }

@@ -208,7 +208,7 @@ static int pep_ctrlreq_error(struct sock *sk, struct sk_buff *oskb, u8 code,
    struct pnpipehdr *ph;
    struct sockaddr_pn dst;
    u8 data[4] = {
-       oph->data[0], /* PEP type */
+       oph->pep_type, /* PEP type */
        code, /* error code, at an unusual offset */
        PAD, PAD,
    };
@@ -221,7 +221,7 @@ static int pep_ctrlreq_error(struct sock *sk, struct sk_buff *oskb, u8 code,
    ph->utid = oph->utid;
    ph->message_id = PNS_PEP_CTRL_RESP;
    ph->pipe_handle = oph->pipe_handle;
-   ph->data[0] = oph->data[1]; /* CTRL id */
+   ph->data0 = oph->data[0]; /* CTRL id */

    pn_skb_get_src_sockaddr(oskb, &dst);
    return pn_skb_send(sk, skb, &dst);
@@ -272,17 +272,17 @@ static int pipe_rcv_status(struct sock *sk, struct sk_buff *skb)
        return -EINVAL;

    hdr = pnp_hdr(skb);
-   if (hdr->data[0] != PN_PEP_TYPE_COMMON) {
+   if (hdr->pep_type != PN_PEP_TYPE_COMMON) {
        net_dbg_ratelimited("Phonet unknown PEP type: %u\n",
-                   (unsigned int)hdr->data[0]);
+                   (unsigned int)hdr->pep_type);
        return -EOPNOTSUPP;
    }

-   switch (hdr->data[1]) {
+   switch (hdr->data[0]) {
    case PN_PEP_IND_FLOW_CONTROL:
        switch (pn->tx_fc) {
        case PN_LEGACY_FLOW_CONTROL:
-           switch (hdr->data[4]) {
+           switch (hdr->data[3]) {
            case PEP_IND_BUSY:
                atomic_set(&pn->tx_credits, 0);
                break;
@@ -292,7 +292,7 @@ static int pipe_rcv_status(struct sock *sk, struct sk_buff *skb)
            }
            break;
        case PN_ONE_CREDIT_FLOW_CONTROL:
-           if (hdr->data[4] == PEP_IND_READY)
+           if (hdr->data[3] == PEP_IND_READY)
                atomic_set(&pn->tx_credits, wake = 1);
            break;
        }
@@ -301,12 +301,12 @@ static int pipe_rcv_status(struct sock *sk, struct sk_buff *skb)
    case PN_PEP_IND_ID_MCFC_GRANT_CREDITS:
        if (pn->tx_fc != PN_MULTI_CREDIT_FLOW_CONTROL)
            break;
-       atomic_add(wake = hdr->data[4], &pn->tx_credits);
+       atomic_add(wake = hdr->data[3], &pn->tx_credits);
        break;

    default:
        net_dbg_ratelimited("Phonet unknown PEP indication: %u\n",
-                   (unsigned int)hdr->data[1]);
+                   (unsigned int)hdr->data[0]);
        return -EOPNOTSUPP;
    }
    if (wake)
@@ -318,7 +318,7 @@ static int pipe_rcv_created(struct sock *sk, struct sk_buff *skb)
 {
    struct pep_sock *pn = pep_sk(sk);
    struct pnpipehdr *hdr = pnp_hdr(skb);
-   u8 n_sb = hdr->data[0];
+   u8 n_sb = hdr->data0;

    pn->rx_fc = pn->tx_fc = PN_LEGACY_FLOW_CONTROL;
    __skb_pull(skb, sizeof(*hdr));
@@ -506,7 +506,7 @@ static int pep_connresp_rcv(struct sock *sk, struct sk_buff *skb)
        return -ECONNREFUSED;

    /* Parse sub-blocks */
-   n_sb = hdr->data[4];
+   n_sb = hdr->data[3];
    while (n_sb > 0) {
        u8 type, buf[6], len = sizeof(buf);
        const u8 *data = pep_get_sb(skb, &type, &len, buf);
@@ -739,7 +739,7 @@ static int pipe_do_remove(struct sock *sk)
    ph->utid = 0;
    ph->message_id = PNS_PIPE_REMOVE_REQ;
    ph->pipe_handle = pn->pipe_handle;
-   ph->data[0] = PAD;
+   ph->data0 = PAD;
    return pn_skb_send(sk, skb, NULL);
 }

@@ -817,7 +817,7 @@ static struct sock *pep_sock_accept(struct sock *sk, int flags, int *errp,
    peer_type = hdr->other_pep_type << 8;

    /* Parse sub-blocks (options) */
-   n_sb = hdr->data[4];
+   n_sb = hdr->data[3];
    while (n_sb > 0) {
        u8 type, buf[1], len = sizeof(buf);
        const u8 *data = pep_get_sb(skb, &type, &len, buf);
@@ -1109,7 +1109,7 @@ static int pipe_skb_send(struct sock *sk, struct sk_buff *skb)
    ph->utid = 0;
    if (pn->aligned) {
        ph->message_id = PNS_PIPE_ALIGNED_DATA;
-       ph->data[0] = 0; /* padding */
+       ph->data0 = 0; /* padding */
    } else
        ph->message_id = PNS_PIPE_DATA;
    ph->pipe_handle = pn->pipe_handle;

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