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drop_monitor: work around gcc-10 stringop-overflow warning 

The current gcc-10 snapshot produces a false-positive warning:

net/core/drop_monitor.c: In function 'trace_drop_common.constprop':
cc1: error: writing 8 bytes into a region of size 0 [-Werror=stringop-overflow=]
In file included from net/core/drop_monitor.c:23:
include/uapi/linux/net_dropmon.h:36:8: note: at offset 0 to object 'entries' with size 4 declared here
   36 |  __u32 entries;
      |        ^~~~~~~

I reported this in the gcc bugzilla, but in case it does not get
fixed in the release, work around it by using a temporary variable.

Fixes: 9a8afc8d39 ("Network Drop Monitor: Adding drop monitor implementation & Netlink protocol")
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94881
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Arnd Bergmann 2020-04-30 23:30:49 +02:00 committed by David S. Miller
parent 846c68f7f1
commit dc30b4059f
1 changed files with 7 additions and 4 deletions
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11
net/core/drop_monitor.c
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@ -213,6 +213,7 @@ static void sched_send_work(struct timer_list *t)
static void trace_drop_common(struct sk_buff *skb, void *location)
{
struct net_dm_alert_msg *msg;
struct net_dm_drop_point *point;
struct nlmsghdr *nlh;
struct nlattr *nla;
int i;
@ -231,11 +232,13 @@ static void trace_drop_common(struct sk_buff *skb, void *location)
nlh = (struct nlmsghdr *)dskb->data;
nla = genlmsg_data(nlmsg_data(nlh));
msg = nla_data(nla);
point = msg->points;
for (i = 0; i < msg->entries; i++) {
if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
msg->points[i].count++;
if (!memcmp(&location, &point->pc, sizeof(void *))) {
point->count++;
goto out;
}
point++;
}
if (msg->entries == dm_hit_limit)
goto out;
@ -244,8 +247,8 @@ static void trace_drop_common(struct sk_buff *skb, void *location)
*/
__nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point));
nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
msg->points[msg->entries].count = 1;
memcpy(point->pc, &location, sizeof(void *));
point->count = 1;
msg->entries++;
if (!timer_pending(&data->send_timer)) {