[PATCH AUTOSEL 6.11 056/244] netpoll: Ensure clean state on setup failures

Sasha Levin
2024-09-25T11:38:39Z

From: Breno Leitao <leitao@debian.org>

[ Upstream commit ae5a0456e0b4cfd7e61619e55251ffdf1bc7adfb ]

Modify netpoll_setup() and __netpoll_setup() to ensure that the netpoll
structure (np) is left in a clean state if setup fails for any reason.
This prevents carrying over misconfigured fields in case of partial
setup success.

Key changes:
- np->dev is now set only after successful setup, ensuring it's always
NULL if netpoll is not configured or if netpoll_setup() fails.
- np->local_ip is zeroed if netpoll setup doesn't complete successfully.
- Added DEBUG_NET_WARN_ON_ONCE() checks to catch unexpected states.
- Reordered some operations in __netpoll_setup() for better logical flow.

These changes improve the reliability of netpoll configuration, since it
assures that the structure is fully initialized or totally unset.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20240822111051.179850-2-leitao@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/netpoll.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index d657b042d5a04..930acc87c8c08 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -624,12 +624,9 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
const struct net_device_ops *ops;
int err;

- np->dev = ndev;
- strscpy(np->dev_name, ndev->name, IFNAMSIZ);
-
if (ndev->priv_flags & IFF_DISABLE_NETPOLL) {
np_err(np, "%s doesn't support polling, aborting\n",
- np->dev_name);
+ ndev->name);
err = -ENOTSUPP;
goto out;
}
@@ -647,7 +644,7 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)

refcount_set(&npinfo->refcnt, 1);

- ops = np->dev->netdev_ops;
+ ops = ndev->netdev_ops;
if (ops->ndo_netpoll_setup) {
err = ops->ndo_netpoll_setup(ndev, npinfo);
if (err)
@@ -658,6 +655,8 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
refcount_inc(&npinfo->refcnt);
}

+ np->dev = ndev;
+ strscpy(np->dev_name, ndev->name, IFNAMSIZ);
npinfo->netpoll = np;

/* last thing to do is link it to the net device structure */
@@ -675,6 +674,7 @@ EXPORT_SYMBOL_GPL(__netpoll_setup);
int netpoll_setup(struct netpoll *np)
{
struct net_device *ndev = NULL;
+ bool ip_overwritten = false;
struct in_device *in_dev;
int err;

@@ -739,6 +739,7 @@ int netpoll_setup(struct netpoll *np)
}

np->local_ip.ip = ifa->ifa_local;
+ ip_overwritten = true;
np_info(np, "local IP %pI4\n", &np->local_ip.ip);
} else {
#if IS_ENABLED(CONFIG_IPV6)
@@ -755,6 +756,7 @@ int netpoll_setup(struct netpoll *np)
!!(ipv6_addr_type(&np->remote_ip.in6) & IPV6_ADDR_LINKLOCAL))
continue;
np->local_ip.in6 = ifp->addr;
+ ip_overwritten = true;
err = 0;
break;
}
@@ -785,6 +787,9 @@ int netpoll_setup(struct netpoll *np)
return 0;

put:
+ DEBUG_NET_WARN_ON_ONCE(np->dev);
+ if (ip_overwritten)
+ memset(&np->local_ip, 0, sizeof(np->local_ip));
netdev_put(ndev, &np->dev_tracker);
unlock:
rtnl_unlock();
--
2.43.0