The MANA driver's probe registers netdevice via the following call chain:
mana_probe() register_netdev() register_netdevice()
register_netdevice() calls notifier callback for netvsc driver, holding the netdev mutex via netdev_lock_ops().
Further this netvsc notifier callback end up attempting to acquire the same lock again in dev_xdp_propagate() leading to deadlock.
netvsc_netdev_event() netvsc_vf_setxdp() dev_xdp_propagate()
This deadlock was not observed so far because net_shaper_ops was never set and this lock in noop in this case. Fix this by using netif_xdp_propagate instead of dev_xdp_propagate to avoid recursive locking in this path.
This issue has not observed so far because net_shaper_ops was unset, making the lock path effectively a no-op. To prevent recursive locking and avoid this deadlock, replace dev_xdp_propagate() with netif_xdp_propagate(), which does not acquire the lock again.
Also, clean up the unregistration path by removing unnecessary call to netvsc_vf_setxdp(), since unregister_netdevice_many_notify() already performs this cleanup via dev_xdp_uninstall.
Fixes: 97246d6d21c2 ("net: hold netdev instance lock during ndo_bpf") Cc: stable@vger.kernel.org Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com --- drivers/net/hyperv/netvsc_bpf.c | 2 +- drivers/net/hyperv/netvsc_drv.c | 2 -- net/core/dev.c | 1 + 3 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/net/hyperv/netvsc_bpf.c b/drivers/net/hyperv/netvsc_bpf.c index e01c5997a551..1dd3755d9e6d 100644 --- a/drivers/net/hyperv/netvsc_bpf.c +++ b/drivers/net/hyperv/netvsc_bpf.c @@ -183,7 +183,7 @@ int netvsc_vf_setxdp(struct net_device *vf_netdev, struct bpf_prog *prog) xdp.command = XDP_SETUP_PROG; xdp.prog = prog;
- ret = dev_xdp_propagate(vf_netdev, &xdp); + ret = netif_xdp_propagate(vf_netdev, &xdp);
if (ret && prog) bpf_prog_put(prog); diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index d8b169ac0343..ee3aaf9c10e6 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -2462,8 +2462,6 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev)
netdev_info(ndev, "VF unregistering: %s\n", vf_netdev->name);
- netvsc_vf_setxdp(vf_netdev, NULL); - reinit_completion(&net_device_ctx->vf_add); netdev_rx_handler_unregister(vf_netdev); netdev_upper_dev_unlink(vf_netdev, ndev); diff --git a/net/core/dev.c b/net/core/dev.c index fccf2167b235..8c6c9d7fba26 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -9953,6 +9953,7 @@ int netif_xdp_propagate(struct net_device *dev, struct netdev_bpf *bpf)
return dev->netdev_ops->ndo_bpf(dev, bpf); } +EXPORT_SYMBOL_GPL(netif_xdp_propagate);
u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode) {
-----Original Message----- From: Saurabh Sengar ssengar@linux.microsoft.com Sent: Saturday, May 17, 2025 11:48 PM To: KY Srinivasan kys@microsoft.com; Haiyang Zhang haiyangz@microsoft.com; wei.liu@kernel.org; Dexuan Cui decui@microsoft.com; andrew+netdev@lunn.ch; davem@davemloft.net; edumazet@google.com; pabeni@redhat.com; horms@kernel.org; ast@kernel.org; daniel@iogearbox.net; hawk@kernel.org; john.fastabend@gmail.com; sdf@fomichev.me; kuniyu@amazon.com; ahmed.zaki@intel.com; aleksander.lobakin@intel.com; linux-hyperv@vger.kernel.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; bpf@vger.kernel.org Cc: Saurabh Singh Sengar ssengar@microsoft.com; stable@vger.kernel.org; Saurabh Sengar ssengar@linux.microsoft.com Subject: [PATCH net] hv_netvsc: fix potential deadlock in netvsc_vf_setxdp()
The MANA driver's probe registers netdevice via the following call chain:
mana_probe() register_netdev() register_netdevice()
register_netdevice() calls notifier callback for netvsc driver, holding the netdev mutex via netdev_lock_ops().
Further this netvsc notifier callback end up attempting to acquire the same lock again in dev_xdp_propagate() leading to deadlock.
netvsc_netdev_event() netvsc_vf_setxdp() dev_xdp_propagate()
This deadlock was not observed so far because net_shaper_ops was never set and this lock in noop in this case. Fix this by using netif_xdp_propagate instead of dev_xdp_propagate to avoid recursive locking in this path.
This issue has not observed so far because net_shaper_ops was unset, making the lock path effectively a no-op. To prevent recursive locking and avoid this deadlock, replace dev_xdp_propagate() with netif_xdp_propagate(), which does not acquire the lock again.
Also, clean up the unregistration path by removing unnecessary call to netvsc_vf_setxdp(), since unregister_netdevice_many_notify() already performs this cleanup via dev_xdp_uninstall.
Fixes: 97246d6d21c2 ("net: hold netdev instance lock during ndo_bpf") Cc: stable@vger.kernel.org Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com
Reviewed-by: Haiyang Zhang haiyangz@microsoft.com
On 18-05-2025 09:17, Saurabh Sengar wrote:
The MANA driver's probe registers netdevice via the following call chain:
mana_probe() register_netdev() register_netdevice()
register_netdevice() calls notifier callback for netvsc driver, holding the netdev mutex via netdev_lock_ops().
Further this netvsc notifier callback end up attempting to acquire the same lock again in dev_xdp_propagate() leading to deadlock.
netvsc_netdev_event() netvsc_vf_setxdp() dev_xdp_propagate()
This deadlock was not observed so far because net_shaper_ops was never set and this lock in noop in this case. Fix this by using netif_xdp_propagate instead of dev_xdp_propagate to avoid recursive locking in this path.
This issue has not observed so far because net_shaper_ops was unset, making the lock path effectively a no-op. To prevent recursive locking and avoid this deadlock, replace dev_xdp_propagate() with netif_xdp_propagate(), which does not acquire the lock again.
avoid noop and repetition (because the paragraph about net_shaper_ops is repeated):
"This deadlock was not observed so far because net_shaper_ops was never set, and thus the lock was effectively a no-op in this case. Fix this by using netif_xdp_propagate() instead of dev_xdp_propagate() to avoid recursive locking in this path.
Also, clean up the unregistration path by removing the unnecessary call to netvsc_vf_setxdp(), since unregister_netdevice_many_notify() already performs this cleanup via dev_xdp_uninstall()."
Also, clean up the unregistration path by removing unnecessary call to netvsc_vf_setxdp(), since unregister_netdevice_many_notify() already performs this cleanup via dev_xdp_uninstall.
Fixes: 97246d6d21c2 ("net: hold netdev instance lock during ndo_bpf") Cc: stable@vger.kernel.org Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com
drivers/net/hyperv/netvsc_bpf.c | 2 +- drivers/net/hyperv/netvsc_drv.c | 2 -- net/core/dev.c | 1 + 3 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/net/hyperv/netvsc_bpf.c b/drivers/net/hyperv/netvsc_bpf.c index e01c5997a551..1dd3755d9e6d 100644 --- a/drivers/net/hyperv/netvsc_bpf.c +++ b/drivers/net/hyperv/netvsc_bpf.c @@ -183,7 +183,7 @@ int netvsc_vf_setxdp(struct net_device *vf_netdev, struct bpf_prog *prog)
Thanks, Alok
On Sat, May 17, 2025 at 08:47:50PM -0700, Saurabh Sengar wrote:
The MANA driver's probe registers netdevice via the following call chain:
mana_probe() register_netdev() register_netdevice()
register_netdevice() calls notifier callback for netvsc driver, holding the netdev mutex via netdev_lock_ops().
Further this netvsc notifier callback end up attempting to acquire the same lock again in dev_xdp_propagate() leading to deadlock.
netvsc_netdev_event() netvsc_vf_setxdp() dev_xdp_propagate()
This deadlock was not observed so far because net_shaper_ops was never set and this lock in noop in this case. Fix this by using netif_xdp_propagate instead of dev_xdp_propagate to avoid recursive locking in this path.
This issue has not observed so far because net_shaper_ops was unset, making the lock path effectively a no-op. To prevent recursive locking and avoid this deadlock, replace dev_xdp_propagate() with netif_xdp_propagate(), which does not acquire the lock again.
Also, clean up the unregistration path by removing unnecessary call to netvsc_vf_setxdp(), since unregister_netdevice_many_notify() already performs this cleanup via dev_xdp_uninstall.
Fixes: 97246d6d21c2 ("net: hold netdev instance lock during ndo_bpf") Cc: stable@vger.kernel.org Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com
Built and booted successfully.
Tested-by: Erni Sri Satya Vennela ernis@linux.microsoft.com
Thanks!
linux-stable-mirror@lists.linaro.org
-
ALOK TIWARI -
Erni Sri Satya Vennela -
Haiyang Zhang -
Saurabh Sengar