[PATCH] wifi: atmel: Avoid clashing function prototypes

From: Kees Cook
Date: Sat Oct 01 2022 - 23:24:48 EST

When built with Control Flow Integrity, function prototypes between
caller and function declaration must match. These mismatches are visible
at compile time with the new -Wcast-function-type-strict in Clang[1].

Of the 1549 warnings found, 188 come from the atmel driver. For example:

drivers/net/wireless/atmel/atmel.c:2518:2: warning: cast from 'int (*)(struct net_device *, struct iw_request_info *, void *, char *)' to 'iw_handler' (aka 'int (*)(struct net_device *, struct iw_request_info *, union iwreq_data *, char *)') converts to incompatible function type [-Wcast-function-type-strict]
(iw_handler) atmel_config_commit, /* SIOCSIWCOMMIT */
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The atmel Wireless Extension handler callbacks (iw_handler) use a union
for the data argument. Actually use the union and perform explicit
member selection in the function body instead of having a function
prototype mismatch. There are no resulting binary differences.

This patch is a cleanup based on Brad Spengler/PaX Team's modifications
to the atmel driver in their last public patch of grsecurity/PaX based
on my understanding of the code. Changes or omissions from the original
code are mine and don't reflect the original grsecurity/PaX code.

[1] https://reviews.llvm.org/D134831

Cc: Simon Kelley <simon@xxxxxxxxxxxxxxxxx>
Cc: Kalle Valo <kvalo@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: linux-wireless@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
drivers/net/wireless/atmel/atmel.c | 164 ++++++++++++++---------------
1 file changed, 80 insertions(+), 84 deletions(-)

diff --git a/drivers/net/wireless/atmel/atmel.c b/drivers/net/wireless/atmel/atmel.c
index 0361c8eb2008..7823220686e6 100644
--- a/drivers/net/wireless/atmel/atmel.c
+++ b/drivers/net/wireless/atmel/atmel.c
@@ -1643,9 +1643,10 @@ EXPORT_SYMBOL(stop_atmel_card);

static int atmel_set_essid(struct net_device *dev,
struct iw_request_info *info,
- struct iw_point *dwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_point *dwrq = &wrqu->essid;
struct atmel_private *priv = netdev_priv(dev);

/* Check if we asked for `any' */
@@ -1671,9 +1672,10 @@ static int atmel_set_essid(struct net_device *dev,

static int atmel_get_essid(struct net_device *dev,
struct iw_request_info *info,
- struct iw_point *dwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_point *dwrq = &wrqu->essid;
struct atmel_private *priv = netdev_priv(dev);

/* Get the current SSID */
@@ -1692,9 +1694,10 @@ static int atmel_get_essid(struct net_device *dev,

static int atmel_get_wap(struct net_device *dev,
struct iw_request_info *info,
- struct sockaddr *awrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct sockaddr *awrq = &wrqu->ap_addr;
struct atmel_private *priv = netdev_priv(dev);
memcpy(awrq->sa_data, priv->CurrentBSSID, ETH_ALEN);
awrq->sa_family = ARPHRD_ETHER;
@@ -1704,9 +1707,10 @@ static int atmel_get_wap(struct net_device *dev,

static int atmel_set_encode(struct net_device *dev,
struct iw_request_info *info,
- struct iw_point *dwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_point *dwrq = &wrqu->encoding;
struct atmel_private *priv = netdev_priv(dev);

/* Basic checking: do we have a key to set ?
@@ -1793,9 +1797,10 @@ static int atmel_set_encode(struct net_device *dev,

static int atmel_get_encode(struct net_device *dev,
struct iw_request_info *info,
- struct iw_point *dwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_point *dwrq = &wrqu->encoding;
struct atmel_private *priv = netdev_priv(dev);
int index = (dwrq->flags & IW_ENCODE_INDEX) - 1;

@@ -2003,18 +2008,19 @@ static int atmel_get_auth(struct net_device *dev,

static int atmel_get_name(struct net_device *dev,
struct iw_request_info *info,
- char *cwrq,
+ union iwreq_data *wrqu,
char *extra)
{
- strcpy(cwrq, "IEEE 802.11-DS");
+ strcpy(wrqu->name, "IEEE 802.11-DS");
return 0;
}

static int atmel_set_rate(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->bitrate;
struct atmel_private *priv = netdev_priv(dev);

if (vwrq->fixed == 0) {
@@ -2053,9 +2059,10 @@ static int atmel_set_rate(struct net_device *dev,

static int atmel_set_mode(struct net_device *dev,
struct iw_request_info *info,
- __u32 *uwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ __u32 *uwrq = &wrqu->mode;
struct atmel_private *priv = netdev_priv(dev);

if (*uwrq != IW_MODE_ADHOC && *uwrq != IW_MODE_INFRA)
@@ -2067,9 +2074,10 @@ static int atmel_set_mode(struct net_device *dev,

static int atmel_get_mode(struct net_device *dev,
struct iw_request_info *info,
- __u32 *uwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ __u32 *uwrq = &wrqu->mode;
struct atmel_private *priv = netdev_priv(dev);

*uwrq = priv->operating_mode;
@@ -2078,9 +2086,10 @@ static int atmel_get_mode(struct net_device *dev,

static int atmel_get_rate(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->bitrate;
struct atmel_private *priv = netdev_priv(dev);

if (priv->auto_tx_rate) {
@@ -2108,9 +2117,10 @@ static int atmel_get_rate(struct net_device *dev,

static int atmel_set_power(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->power;
struct atmel_private *priv = netdev_priv(dev);
priv->power_mode = vwrq->disabled ? 0 : 1;
return -EINPROGRESS;
@@ -2118,9 +2128,10 @@ static int atmel_set_power(struct net_device *dev,

static int atmel_get_power(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->power;
struct atmel_private *priv = netdev_priv(dev);
vwrq->disabled = priv->power_mode ? 0 : 1;
vwrq->flags = IW_POWER_ON;
@@ -2129,9 +2140,10 @@ static int atmel_get_power(struct net_device *dev,

static int atmel_set_retry(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->retry;
struct atmel_private *priv = netdev_priv(dev);

if (!vwrq->disabled && (vwrq->flags & IW_RETRY_LIMIT)) {
@@ -2152,9 +2164,10 @@ static int atmel_set_retry(struct net_device *dev,

static int atmel_get_retry(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->retry;
struct atmel_private *priv = netdev_priv(dev);

vwrq->disabled = 0; /* Can't be disabled */
@@ -2175,9 +2188,10 @@ static int atmel_get_retry(struct net_device *dev,

static int atmel_set_rts(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->rts;
struct atmel_private *priv = netdev_priv(dev);
int rthr = vwrq->value;

@@ -2193,9 +2207,10 @@ static int atmel_set_rts(struct net_device *dev,

static int atmel_get_rts(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->rts;
struct atmel_private *priv = netdev_priv(dev);

vwrq->value = priv->rts_threshold;
@@ -2207,9 +2222,10 @@ static int atmel_get_rts(struct net_device *dev,

static int atmel_set_frag(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->frag;
struct atmel_private *priv = netdev_priv(dev);
int fthr = vwrq->value;

@@ -2226,9 +2242,10 @@ static int atmel_set_frag(struct net_device *dev,

static int atmel_get_frag(struct net_device *dev,
struct iw_request_info *info,
- struct iw_param *vwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_param *vwrq = &wrqu->frag;
struct atmel_private *priv = netdev_priv(dev);

vwrq->value = priv->frag_threshold;
@@ -2240,9 +2257,10 @@ static int atmel_get_frag(struct net_device *dev,

static int atmel_set_freq(struct net_device *dev,
struct iw_request_info *info,
- struct iw_freq *fwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_freq *fwrq = &wrqu->freq;
struct atmel_private *priv = netdev_priv(dev);
int rc = -EINPROGRESS; /* Call commit handler */

@@ -2270,9 +2288,10 @@ static int atmel_set_freq(struct net_device *dev,

static int atmel_get_freq(struct net_device *dev,
struct iw_request_info *info,
- struct iw_freq *fwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_freq *fwrq = &wrqu->freq;
struct atmel_private *priv = netdev_priv(dev);

fwrq->m = priv->channel;
@@ -2282,7 +2301,7 @@ static int atmel_get_freq(struct net_device *dev,

static int atmel_set_scan(struct net_device *dev,
struct iw_request_info *info,
- struct iw_point *dwrq,
+ union iwreq_data *dwrq,
char *extra)
{
struct atmel_private *priv = netdev_priv(dev);
@@ -2320,9 +2339,10 @@ static int atmel_set_scan(struct net_device *dev,

static int atmel_get_scan(struct net_device *dev,
struct iw_request_info *info,
- struct iw_point *dwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_point *dwrq = &wrqu->data;
struct atmel_private *priv = netdev_priv(dev);
int i;
char *current_ev = extra;
@@ -2391,9 +2411,10 @@ static int atmel_get_scan(struct net_device *dev,

static int atmel_get_range(struct net_device *dev,
struct iw_request_info *info,
- struct iw_point *dwrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct iw_point *dwrq = &wrqu->data;
struct atmel_private *priv = netdev_priv(dev);
struct iw_range *range = (struct iw_range *) extra;
int k, i, j;
@@ -2465,9 +2486,10 @@ static int atmel_get_range(struct net_device *dev,

static int atmel_set_wap(struct net_device *dev,
struct iw_request_info *info,
- struct sockaddr *awrq,
+ union iwreq_data *wrqu,
char *extra)
{
+ struct sockaddr *awrq = &wrqu->ap_addr;
struct atmel_private *priv = netdev_priv(dev);
int i;
static const u8 any[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
@@ -2507,7 +2529,7 @@ static int atmel_set_wap(struct net_device *dev,

static int atmel_config_commit(struct net_device *dev,
struct iw_request_info *info, /* NULL */
- void *zwrq, /* NULL */
+ union iwreq_data *zwrq, /* NULL */
char *extra) /* NULL */
{
return atmel_open(dev);
@@ -2515,66 +2537,40 @@ static int atmel_config_commit(struct net_device *dev,

static const iw_handler atmel_handler[] =
{
- (iw_handler) atmel_config_commit, /* SIOCSIWCOMMIT */
- (iw_handler) atmel_get_name, /* SIOCGIWNAME */
- (iw_handler) NULL, /* SIOCSIWNWID */
- (iw_handler) NULL, /* SIOCGIWNWID */
- (iw_handler) atmel_set_freq, /* SIOCSIWFREQ */
- (iw_handler) atmel_get_freq, /* SIOCGIWFREQ */
- (iw_handler) atmel_set_mode, /* SIOCSIWMODE */
- (iw_handler) atmel_get_mode, /* SIOCGIWMODE */
- (iw_handler) NULL, /* SIOCSIWSENS */
- (iw_handler) NULL, /* SIOCGIWSENS */
- (iw_handler) NULL, /* SIOCSIWRANGE */
- (iw_handler) atmel_get_range, /* SIOCGIWRANGE */
- (iw_handler) NULL, /* SIOCSIWPRIV */
- (iw_handler) NULL, /* SIOCGIWPRIV */
- (iw_handler) NULL, /* SIOCSIWSTATS */
- (iw_handler) NULL, /* SIOCGIWSTATS */
- (iw_handler) NULL, /* SIOCSIWSPY */
- (iw_handler) NULL, /* SIOCGIWSPY */
- (iw_handler) NULL, /* -- hole -- */
- (iw_handler) NULL, /* -- hole -- */
- (iw_handler) atmel_set_wap, /* SIOCSIWAP */
- (iw_handler) atmel_get_wap, /* SIOCGIWAP */
- (iw_handler) NULL, /* -- hole -- */
- (iw_handler) NULL, /* SIOCGIWAPLIST */
- (iw_handler) atmel_set_scan, /* SIOCSIWSCAN */
- (iw_handler) atmel_get_scan, /* SIOCGIWSCAN */
- (iw_handler) atmel_set_essid, /* SIOCSIWESSID */
- (iw_handler) atmel_get_essid, /* SIOCGIWESSID */
- (iw_handler) NULL, /* SIOCSIWNICKN */
- (iw_handler) NULL, /* SIOCGIWNICKN */
- (iw_handler) NULL, /* -- hole -- */
- (iw_handler) NULL, /* -- hole -- */
- (iw_handler) atmel_set_rate, /* SIOCSIWRATE */
- (iw_handler) atmel_get_rate, /* SIOCGIWRATE */
- (iw_handler) atmel_set_rts, /* SIOCSIWRTS */
- (iw_handler) atmel_get_rts, /* SIOCGIWRTS */
- (iw_handler) atmel_set_frag, /* SIOCSIWFRAG */
- (iw_handler) atmel_get_frag, /* SIOCGIWFRAG */
- (iw_handler) NULL, /* SIOCSIWTXPOW */
- (iw_handler) NULL, /* SIOCGIWTXPOW */
- (iw_handler) atmel_set_retry, /* SIOCSIWRETRY */
- (iw_handler) atmel_get_retry, /* SIOCGIWRETRY */
- (iw_handler) atmel_set_encode, /* SIOCSIWENCODE */
- (iw_handler) atmel_get_encode, /* SIOCGIWENCODE */
- (iw_handler) atmel_set_power, /* SIOCSIWPOWER */
- (iw_handler) atmel_get_power, /* SIOCGIWPOWER */
- (iw_handler) NULL, /* -- hole -- */
- (iw_handler) NULL, /* -- hole -- */
- (iw_handler) NULL, /* SIOCSIWGENIE */
- (iw_handler) NULL, /* SIOCGIWGENIE */
- (iw_handler) atmel_set_auth, /* SIOCSIWAUTH */
- (iw_handler) atmel_get_auth, /* SIOCGIWAUTH */
- (iw_handler) atmel_set_encodeext, /* SIOCSIWENCODEEXT */
- (iw_handler) atmel_get_encodeext, /* SIOCGIWENCODEEXT */
- (iw_handler) NULL, /* SIOCSIWPMKSA */
+ IW_HANDLER(SIOCSIWCOMMIT, atmel_config_commit),
+ IW_HANDLER(SIOCGIWNAME, atmel_get_name),
+ IW_HANDLER(SIOCSIWFREQ, atmel_set_freq),
+ IW_HANDLER(SIOCGIWFREQ, atmel_get_freq),
+ IW_HANDLER(SIOCSIWMODE, atmel_set_mode),
+ IW_HANDLER(SIOCGIWMODE, atmel_get_mode),
+ IW_HANDLER(SIOCGIWRANGE, atmel_get_range),
+ IW_HANDLER(SIOCSIWAP, atmel_set_wap),
+ IW_HANDLER(SIOCGIWAP, atmel_get_wap),
+ IW_HANDLER(SIOCSIWSCAN, atmel_set_scan),
+ IW_HANDLER(SIOCGIWSCAN, atmel_get_scan),
+ IW_HANDLER(SIOCSIWESSID, atmel_set_essid),
+ IW_HANDLER(SIOCGIWESSID, atmel_get_essid),
+ IW_HANDLER(SIOCSIWRATE, atmel_set_rate),
+ IW_HANDLER(SIOCGIWRATE, atmel_get_rate),
+ IW_HANDLER(SIOCSIWRTS, atmel_set_rts),
+ IW_HANDLER(SIOCGIWRTS, atmel_get_rts),
+ IW_HANDLER(SIOCSIWFRAG, atmel_set_frag),
+ IW_HANDLER(SIOCGIWFRAG, atmel_get_frag),
+ IW_HANDLER(SIOCSIWRETRY, atmel_set_retry),
+ IW_HANDLER(SIOCGIWRETRY, atmel_get_retry),
+ IW_HANDLER(SIOCSIWENCODE, atmel_set_encode),
+ IW_HANDLER(SIOCGIWENCODE, atmel_get_encode),
+ IW_HANDLER(SIOCSIWPOWER, atmel_set_power),
+ IW_HANDLER(SIOCGIWPOWER, atmel_get_power),
+ IW_HANDLER(SIOCSIWAUTH, atmel_set_auth),
+ IW_HANDLER(SIOCGIWAUTH, atmel_get_auth),
+ IW_HANDLER(SIOCSIWENCODEEXT, atmel_set_encodeext),
+ IW_HANDLER(SIOCGIWENCODEEXT, atmel_get_encodeext),
};

static const iw_handler atmel_private_handler[] =
{
- NULL, /* SIOCIWFIRSTPRIV */
+ IW_HANDLER(SIOCIWFIRSTPRIV, NULL),
};

struct atmel_priv_ioctl {
@@ -2614,8 +2610,8 @@ static const struct iw_handler_def atmel_handler_def = {
.num_standard = ARRAY_SIZE(atmel_handler),
.num_private = ARRAY_SIZE(atmel_private_handler),
.num_private_args = ARRAY_SIZE(atmel_private_args),
- .standard = (iw_handler *) atmel_handler,
- .private = (iw_handler *) atmel_private_handler,
+ .standard = atmel_handler,
+ .private = atmel_private_handler,
.private_args = (struct iw_priv_args *) atmel_private_args,
.get_wireless_stats = atmel_get_wireless_stats
};
--
2.34.1