From: Arnd Bergmann arnd@arndb.de
[ Upstream commit dc30b4059f6e2abf3712ab537c8718562b21c45d ]
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: 9a8afc8d3962 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/drop_monitor.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c index ca2c9c8b9a3e9..6d7ff117f3792 100644 --- a/net/core/drop_monitor.c +++ b/net/core/drop_monitor.c @@ -159,6 +159,7 @@ static void sched_send_work(unsigned long _data) 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; @@ -177,11 +178,13 @@ 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; @@ -190,8 +193,8 @@ 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)) {