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[87.205.15.91]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a1e7d48f8dsm4198679a12.17.2026.08.10.06.31.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Aug 2026 06:31:29 -0700 (PDT) From: Krystian Kaniewski To: Jason Gunthorpe , Leon Romanovsky , linux-rdma@vger.kernel.org Cc: Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, syzbot+5fe14f2ff4ccbace9a26@syzkaller.appspotmail.com Subject: [PATCH net v3] RDMA/core: Reject unregistering netdevs in ib_get_eth_speed Date: Mon, 10 Aug 2026 15:31:20 +0200 Message-ID: <20260810133124.44513-1-krystianmkaniewski@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. Also copy the device name before dropping the reference, since the warning path currently dereferences netdev after dev_put(). 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 --- v3: - Reworked the fix following Jakub Kicinski's review: a netdev reference protects the allocation, not the operational lifetime. - Moved the fix from ipvlan to the operational RDMA caller. - Check NETREG_REGISTERED under RTNL before invoking ethtool. - Avoid dereferencing netdev after dev_put() in the warning path. - Added the RDMA maintainers and mailing list. v2: https://lore.kernel.org/all/20260803121140.261329-1-krystianmkaniewski@gmail.com/ drivers/infiniband/core/verbs.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c index 86811d31092c..d50e761be4c8 100644 --- a/drivers/infiniband/core/verbs.c +++ b/drivers/infiniband/core/verbs.c @@ -2040,6 +2040,7 @@ int ib_get_eth_speed(struct ib_device *dev, u32 port_num, u16 *speed, u8 *width) u32 netdev_speed; struct net_device *netdev; struct ethtool_link_ksettings lksettings = {}; + char name[IFNAMSIZ]; if (rdma_port_get_link_layer(dev, port_num) != IB_LINK_LAYER_ETHERNET) return -EINVAL; @@ -2049,7 +2050,15 @@ 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); + if (rc) + strscpy(name, netdev->name, sizeof(name)); rtnl_unlock(); dev_put(netdev); @@ -2060,7 +2069,7 @@ int ib_get_eth_speed(struct ib_device *dev, u32 port_num, u16 *speed, u8 *width) netdev_speed = SPEED_1000; if (rc) pr_warn("%s speed is unknown, defaulting to %u\n", - netdev->name, netdev_speed); + name, netdev_speed); } ib_get_width_and_speed(netdev_speed, lksettings.lanes, -- 2.53.0