From ef9fbe1b93f3b617b96e86d5cd76b3fa44514cb5 Mon Sep 17 00:00:00 2001 From: Krystian Kaniewski Date: Wed, 12 Aug 2026 10:16:41 +0200 Subject: [PATCH] RDMA/core: Reject unregistering netdevs in ib_get_eth_speed ib_device_get_netdev() intentionally returns a referenced net_device even when it is unregistering, so matching and cleanup callers can still find the association. The reference keeps struct net_device allocated, but does not guarantee that the device remains operational. ib_get_eth_speed() uses the returned device operationally by invoking its ethtool callback. Although that call is made under RTNL, the function does not verify the registration state first. An asynchronous RDMA port query can therefore call into a netdev after NETDEV_UNREGISTER and ndo_uninit have completed. Check for NETREG_REGISTERED while holding RTNL and return -ENODEV for a device which is being unregistered. Keeping RTNL across the check and the ethtool operation prevents unregister from starting between them. Keep the speed fallback and warning under RTNL as well, so the warning can safely read netdev->name. Drop the netdev reference before releasing RTNL once all accesses to the device are complete. Fixes: d41861942fc5 ("IB/core: Add generic function to extract IB speed from netdev") Reported-by: syzbot+5fe14f2ff4ccbace9a26@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=5fe14f2ff4ccbace9a26 Signed-off-by: Krystian Kaniewski Link: https://patch.msgid.link/20260812081708.32468-1-krystianmkaniewski@gmail.com Signed-off-by: Leon Romanovsky --- drivers/infiniband/core/verbs.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c index 04abc80c1327..c43e25d37266 100644 --- a/drivers/infiniband/core/verbs.c +++ b/drivers/infiniband/core/verbs.c @@ -2058,11 +2058,13 @@ int ib_get_eth_speed(struct ib_device *dev, u32 port_num, u16 *speed, u8 *width) return -ENODEV; rtnl_lock(); + if (READ_ONCE(netdev->reg_state) != NETREG_REGISTERED) { + dev_put(netdev); + rtnl_unlock(); + return -ENODEV; + } + rc = __ethtool_get_link_ksettings(netdev, &lksettings); - rtnl_unlock(); - - dev_put(netdev); - if (!rc && lksettings.base.speed != (u32)SPEED_UNKNOWN) { netdev_speed = lksettings.base.speed; } else { @@ -2071,6 +2073,8 @@ int ib_get_eth_speed(struct ib_device *dev, u32 port_num, u16 *speed, u8 *width) pr_warn("%s speed is unknown, defaulting to %u\n", netdev->name, netdev_speed); } + dev_put(netdev); + rtnl_unlock(); ib_get_width_and_speed(netdev_speed, lksettings.lanes, speed, width);