[PATCH 5.9 029/252] net/ncsi: Fix netlink registration

Greg Kroah-Hartman
2020-11-23T12:43:29Z

From: Joel Stanley <joel@jms.id.au>

[ Upstream commit 1922a46b8c18cb09d33e06a6cc2e43844ac1b9d0 ]

If a user unbinds and re-binds a NC-SI aware driver the kernel will
attempt to register the netlink interface at runtime. The structure is
marked __ro_after_init so registration fails spectacularly at this point.

# echo 1e660000.ethernet > /sys/bus/platform/drivers/ftgmac100/unbind
# echo 1e660000.ethernet > /sys/bus/platform/drivers/ftgmac100/bind
ftgmac100 1e660000.ethernet: Read MAC address 52:54:00:12:34:56 from chip
ftgmac100 1e660000.ethernet: Using NCSI interface
8<--- cut here ---
Unable to handle kernel paging request at virtual address 80a8f858
pgd = 8c768dd6
[80a8f858] *pgd=80a0841e(bad)
Internal error: Oops: 80d [#1] SMP ARM
CPU: 0 PID: 116 Comm: sh Not tainted 5.10.0-rc3-next-20201111-00003-gdd25b227ec1e #51
Hardware name: Generic DT based system
PC is at genl_register_family+0x1f8/0x6d4
LR is at 0xff26ffff
pc : [<8073f930>] lr : [<ff26ffff>] psr: 20000153
sp : 8553bc80 ip : 81406244 fp : 8553bd04
r10: 8085d12c r9 : 80a8f73c r8 : 85739000
r7 : 00000017 r6 : 80a8f860 r5 : 80c8ab98 r4 : 80a8f858
r3 : 00000000 r2 : 00000000 r1 : 81406130 r0 : 00000017
Flags: nzCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment none
Control: 00c5387d Table: 85524008 DAC: 00000051
Process sh (pid: 116, stack limit = 0x1f1988d6)
...
Backtrace:
[<8073f738>] (genl_register_family) from [<80860ac0>] (ncsi_init_netlink+0x20/0x48)
r10:8085d12c r9:80c8fb0c r8:85739000 r7:00000000 r6:81218000 r5:85739000
r4:8121c000
[<80860aa0>] (ncsi_init_netlink) from [<8085d740>] (ncsi_register_dev+0x1b0/0x210)
r5:8121c400 r4:8121c000
[<8085d590>] (ncsi_register_dev) from [<805a8060>] (ftgmac100_probe+0x6e0/0x778)
r10:00000004 r9:80950228 r8:8115bc10 r7:8115ab00 r6:9eae2c24 r5:813b6f88
r4:85739000
[<805a7980>] (ftgmac100_probe) from [<805355ec>] (platform_drv_probe+0x58/0xa8)
r9:80c76bb0 r8:00000000 r7:80cd4974 r6:80c76bb0 r5:8115bc10 r4:00000000
[<80535594>] (platform_drv_probe) from [<80532d58>] (really_probe+0x204/0x514)
r7:80cd4974 r6:00000000 r5:80cd4868 r4:8115bc10

Jakub pointed out that ncsi_register_dev is obviously broken, because
there is only one family so it would never work if there was more than
one ncsi netdev.

Fix the crash by registering the netlink family once on boot, and drop
the code to unregister it.

Fixes: 955dc68cb9b2 ("net/ncsi: Add generic netlink family")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Link: https://lore.kernel.org/r/20201112061210.914621-1-joel@jms.id.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ncsi/ncsi-manage.c | 5 -----
net/ncsi/ncsi-netlink.c | 22 +++-------------------
net/ncsi/ncsi-netlink.h | 3 ---
3 files changed, 3 insertions(+), 27 deletions(-)

--- a/net/ncsi/ncsi-manage.c
+++ b/net/ncsi/ncsi-manage.c
@@ -1726,9 +1726,6 @@ struct ncsi_dev *ncsi_register_dev(struc
ndp->ptype.dev = dev;
dev_add_pack(&ndp->ptype);

- /* Set up generic netlink interface */
- ncsi_init_netlink(dev);
-
pdev = to_platform_device(dev->dev.parent);
if (pdev) {
np = pdev->dev.of_node;
@@ -1892,8 +1889,6 @@ void ncsi_unregister_dev(struct ncsi_dev
list_del_rcu(&ndp->node);
spin_unlock_irqrestore(&ncsi_dev_lock, flags);

- ncsi_unregister_netlink(nd->dev);
-
kfree(ndp);
}
EXPORT_SYMBOL_GPL(ncsi_unregister_dev);
--- a/net/ncsi/ncsi-netlink.c
+++ b/net/ncsi/ncsi-netlink.c
@@ -766,24 +766,8 @@ static struct genl_family ncsi_genl_fami
.n_ops = ARRAY_SIZE(ncsi_ops),
};

-int ncsi_init_netlink(struct net_device *dev)
+static int __init ncsi_init_netlink(void)
{
- int rc;
-
- rc = genl_register_family(&ncsi_genl_family);
- if (rc)
- netdev_err(dev, "ncsi: failed to register netlink family\n");
-
- return rc;
-}
-
-int ncsi_unregister_netlink(struct net_device *dev)
-{
- int rc;
-
- rc = genl_unregister_family(&ncsi_genl_family);
- if (rc)
- netdev_err(dev, "ncsi: failed to unregister netlink family\n");
-
- return rc;
+ return genl_register_family(&ncsi_genl_family);
}
+subsys_initcall(ncsi_init_netlink);
--- a/net/ncsi/ncsi-netlink.h
+++ b/net/ncsi/ncsi-netlink.h
@@ -22,7 +22,4 @@ int ncsi_send_netlink_err(struct net_dev
struct nlmsghdr *nlhdr,
int err);

-int ncsi_init_netlink(struct net_device *dev);
-int ncsi_unregister_netlink(struct net_device *dev);
-
#endif /* __NCSI_NETLINK_H__ */