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linux/net/wireless/wext-spy.c
Gustavo A. R. Silva e93bdd7840 wireless: wext-spy: Fix out-of-bounds warning 
Fix the following out-of-bounds warning:

net/wireless/wext-spy.c:178:2: warning: 'memcpy' offset [25, 28] from the object at 'threshold' is out of the bounds of referenced subobject 'low' with type 'struct iw_quality' at offset 20 [-Warray-bounds]

The problem is that the original code is trying to copy data into a
couple of struct members adjacent to each other in a single call to
memcpy(). This causes a legitimate compiler warning because memcpy()
overruns the length of &threshold.low and &spydata->spy_thr_low. As
these are just a couple of struct members, fix this by using direct
assignments, instead of memcpy().

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

Link: https://github.com/KSPP/linux/issues/109
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210422200032.GA168995@embeddedor
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2021-06-23 10:57:17 +02:00

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/*
* This file implement the Wireless Extensions spy API.
*
* Authors : Jean Tourrilhes - HPL - <jt@hpl.hp.com>
* Copyright (c) 1997-2007 Jean Tourrilhes, All Rights Reserved.
*
* (As all part of the Linux kernel, this file is GPL)
*/
#include <linux/wireless.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/export.h>
#include <net/iw_handler.h>
#include <net/arp.h>
#include <net/wext.h>
static inline struct iw_spy_data *get_spydata(struct net_device *dev)
{
/* This is the new way */
if (dev->wireless_data)
return dev->wireless_data->spy_data;
return NULL;
}
int iw_handler_set_spy(struct net_device * dev,
struct iw_request_info * info,
union iwreq_data * wrqu,
char * extra)
{
struct iw_spy_data * spydata = get_spydata(dev);
struct sockaddr * address = (struct sockaddr *) extra;
/* Make sure driver is not buggy or using the old API */
if (!spydata)
return -EOPNOTSUPP;
/* Disable spy collection while we copy the addresses.
* While we copy addresses, any call to wireless_spy_update()
* will NOP. This is OK, as anyway the addresses are changing. */
spydata->spy_number = 0;
/* We want to operate without locking, because wireless_spy_update()
* most likely will happen in the interrupt handler, and therefore
* have its own locking constraints and needs performance.
* The rtnl_lock() make sure we don't race with the other iw_handlers.
* This make sure wireless_spy_update() "see" that the spy list
* is temporarily disabled. */
smp_wmb();
/* Are there are addresses to copy? */
if (wrqu->data.length > 0) {
int i;
/* Copy addresses */
for (i = 0; i < wrqu->data.length; i++)
memcpy(spydata->spy_address[i], address[i].sa_data,
ETH_ALEN);
/* Reset stats */
memset(spydata->spy_stat, 0,
sizeof(struct iw_quality) * IW_MAX_SPY);
}
/* Make sure above is updated before re-enabling */
smp_wmb();
/* Enable addresses */
spydata->spy_number = wrqu->data.length;
return 0;
}
EXPORT_SYMBOL(iw_handler_set_spy);
int iw_handler_get_spy(struct net_device * dev,
struct iw_request_info * info,
union iwreq_data * wrqu,
char * extra)
{
struct iw_spy_data * spydata = get_spydata(dev);
struct sockaddr * address = (struct sockaddr *) extra;
int i;
/* Make sure driver is not buggy or using the old API */
if (!spydata)
return -EOPNOTSUPP;
wrqu->data.length = spydata->spy_number;
/* Copy addresses. */
for (i = 0; i < spydata->spy_number; i++) {
memcpy(address[i].sa_data, spydata->spy_address[i], ETH_ALEN);
address[i].sa_family = AF_UNIX;
}
/* Copy stats to the user buffer (just after). */
if (spydata->spy_number > 0)
memcpy(extra + (sizeof(struct sockaddr) *spydata->spy_number),
spydata->spy_stat,
sizeof(struct iw_quality) * spydata->spy_number);
/* Reset updated flags. */
for (i = 0; i < spydata->spy_number; i++)
spydata->spy_stat[i].updated &= ~IW_QUAL_ALL_UPDATED;
return 0;
}
EXPORT_SYMBOL(iw_handler_get_spy);
/*------------------------------------------------------------------*/
/*
* Standard Wireless Handler : set spy threshold
*/
int iw_handler_set_thrspy(struct net_device * dev,
struct iw_request_info *info,
union iwreq_data * wrqu,
char * extra)
{
struct iw_spy_data * spydata = get_spydata(dev);
struct iw_thrspy * threshold = (struct iw_thrspy *) extra;
/* Make sure driver is not buggy or using the old API */
if (!spydata)
return -EOPNOTSUPP;
/* Just do it */
spydata->spy_thr_low = threshold->low;
spydata->spy_thr_high = threshold->high;
/* Clear flag */
memset(spydata->spy_thr_under, '\0', sizeof(spydata->spy_thr_under));
return 0;
}
EXPORT_SYMBOL(iw_handler_set_thrspy);
/*------------------------------------------------------------------*/
/*
* Standard Wireless Handler : get spy threshold
*/
int iw_handler_get_thrspy(struct net_device * dev,
struct iw_request_info *info,
union iwreq_data * wrqu,
char * extra)
{
struct iw_spy_data * spydata = get_spydata(dev);
struct iw_thrspy * threshold = (struct iw_thrspy *) extra;
/* Make sure driver is not buggy or using the old API */
if (!spydata)
return -EOPNOTSUPP;
/* Just do it */
threshold->low = spydata->spy_thr_low;
threshold->high = spydata->spy_thr_high;
return 0;
}
EXPORT_SYMBOL(iw_handler_get_thrspy);
/*------------------------------------------------------------------*/
/*
* Prepare and send a Spy Threshold event
*/
static void iw_send_thrspy_event(struct net_device * dev,
struct iw_spy_data * spydata,
unsigned char * address,
struct iw_quality * wstats)
{
union iwreq_data wrqu;
struct iw_thrspy threshold;
/* Init */
wrqu.data.length = 1;
wrqu.data.flags = 0;
/* Copy address */
memcpy(threshold.addr.sa_data, address, ETH_ALEN);
threshold.addr.sa_family = ARPHRD_ETHER;
/* Copy stats */
threshold.qual = *wstats;
/* Copy also thresholds */
threshold.low = spydata->spy_thr_low;
threshold.high = spydata->spy_thr_high;
/* Send event to user space */
wireless_send_event(dev, SIOCGIWTHRSPY, &wrqu, (char *) &threshold);
}
/* ---------------------------------------------------------------- */
/*
* Call for the driver to update the spy data.
* For now, the spy data is a simple array. As the size of the array is
* small, this is good enough. If we wanted to support larger number of
* spy addresses, we should use something more efficient...
*/
void wireless_spy_update(struct net_device * dev,
unsigned char * address,
struct iw_quality * wstats)
{
struct iw_spy_data * spydata = get_spydata(dev);
int i;
int match = -1;
/* Make sure driver is not buggy or using the old API */
if (!spydata)
return;
/* Update all records that match */
for (i = 0; i < spydata->spy_number; i++)
if (ether_addr_equal(address, spydata->spy_address[i])) {
memcpy(&(spydata->spy_stat[i]), wstats,
sizeof(struct iw_quality));
match = i;
}
/* Generate an event if we cross the spy threshold.
* To avoid event storms, we have a simple hysteresis : we generate
* event only when we go under the low threshold or above the
* high threshold. */
if (match >= 0) {
if (spydata->spy_thr_under[match]) {
if (wstats->level > spydata->spy_thr_high.level) {
spydata->spy_thr_under[match] = 0;
iw_send_thrspy_event(dev, spydata,
address, wstats);
}
} else {
if (wstats->level < spydata->spy_thr_low.level) {
spydata->spy_thr_under[match] = 1;
iw_send_thrspy_event(dev, spydata,
address, wstats);
}
}
}
}
EXPORT_SYMBOL(wireless_spy_update);
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