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authorSamuel Mendoza-Jonas <sam@mendozajonas.com>2018-05-30 15:37:05 +1000
committerSamuel Mendoza-Jonas <sam@mendozajonas.com>2018-06-12 13:03:59 +1000
commit32952937bc5c3753ff2f8f4612da5ba51bf69759 (patch)
treeb483f94a243422fad9bcad0da2dd27104c48d46e
parente54e26065cea435fed19b8b2687c87927f1b63f1 (diff)
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discover/network: Null terminate ifname buffer explicitly
GCC 8 produces the following warning for network.c: In function ‘network_handle_nlmsg’, inlined from ‘network_netlink_process’ at ../discover/network.c:726:3: ../discover/network.c:568:3: warning: ‘strncpy’ output may be truncated copying 15 bytes from a string of length 16 [-Wstringop-truncation] strncpy(interface->name, ifname, sizeof(interface->name) - 1); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../discover/network.c:586:3: warning: ‘strncpy’ output may be truncated copying 15 bytes from a string of length 16 [-Wstringop-truncation] strncpy(interface->name, ifname, sizeof(interface->name) - 1); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The code is safe since interface is allocated with talloc_zero() and we could use -Wno-stringop-truncation to hide this but since this is the only offender instead just copy the whole IFNAMSIZ bytes and explicitly terminate the ifname buffer to be safe. Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
-rw-r--r--discover/network.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/discover/network.c b/discover/network.c
index e2cae91..9594b2e 100644
--- a/discover/network.c
+++ b/discover/network.c
@@ -506,7 +506,7 @@ static int network_handle_nlmsg(struct network *network, struct nlmsghdr *nlmsg)
struct rtattr *attr;
unsigned int mtu;
uint8_t ifaddr[6];
- char ifname[IFNAMSIZ+1];
+ char ifname[IFNAMSIZ];
int attrlen, type;
@@ -534,6 +534,7 @@ static int network_handle_nlmsg(struct network *network, struct nlmsghdr *nlmsg)
case IFLA_IFNAME:
strncpy(ifname, data, IFNAMSIZ);
+ ifname[IFNAMSIZ - 1] = '\0';
have_ifname = true;
break;
@@ -565,7 +566,7 @@ static int network_handle_nlmsg(struct network *network, struct nlmsghdr *nlmsg)
interface->ifindex = info->ifi_index;
interface->state = IFSTATE_NEW;
memcpy(interface->hwaddr, ifaddr, sizeof(interface->hwaddr));
- strncpy(interface->name, ifname, sizeof(interface->name) - 1);
+ strncpy(interface->name, ifname, sizeof(interface->name));
list_for_each_entry(&network->interfaces, tmp, list)
if (memcmp(interface->hwaddr, tmp->hwaddr,
@@ -583,7 +584,7 @@ static int network_handle_nlmsg(struct network *network, struct nlmsghdr *nlmsg)
/* A repeated RTM_NEWLINK can represent an interface name change */
if (strncmp(interface->name, ifname, IFNAMSIZ)) {
pb_debug("ifname update: %s -> %s\n", interface->name, ifname);
- strncpy(interface->name, ifname, sizeof(interface->name) - 1);
+ strncpy(interface->name, ifname, sizeof(interface->name));
talloc_free(interface->dev->device->id);
interface->dev->device->id =
talloc_strdup(interface->dev->device, ifname);
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