From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f198.google.com (mail-dy1-f198.google.com [74.125.82.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 68E6A4FDE47 for ; Wed, 14 Oct 2026 16:17:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791994684; cv=none; b=au/aeF6FZ263rlWBJlqGGArPKXCv2UB36pRfIsF/pMHrlEgVd8nFnszNhavjzregwujfJ5leIbdDrqj4YwNv5atgGlxxxWOpe3bSrNXWzqHn5N/KS18zPeIYfA80pfv5o6O/mTv12Hyl2V2bJoFFnPPhBwXjZE7+42RrK6O/sA0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791994684; c=relaxed/simple; bh=9o53G9X/IwLd+/7yC+FWQcBa7VpzBDTn8/Auwb6tw/U=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=UVAW2fBQHWOeQQFis2532lwnaeiw/PslUKLqnwwO9p5j9vtzrk/qjq7oQq8qhdscyVxJgmW9xXw0IiaydpKytR+fSvAwEGf2gUOvAYA8KQRS4CYRbEFjttxyZKWRYz49YLrAdVhr2tbQs4N0cA7JrxuNn5dV2KhoYX3KPbAH1S0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--almasrymina.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=jOULjgb4; arc=none smtp.client-ip=74.125.82.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--almasrymina.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="jOULjgb4" Received: by mail-dy1-f198.google.com with SMTP id 5a478bee46e88-30c0d568830so8854938eec.1 for ; Wed, 14 Oct 2026 09:17:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1791994677; x=1792599477; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=oGTWqBG9/pmcsFuKv5MXNPnEB5Ld1efa93sWaiCHZ/Q=; b=jOULjgb4+56pevVM3WGvPG746Hx75BdKg0EYaRS60vRh4IQE3nfUpavO8GAStRSsIF C6IFmZt+uZk4SUGwMKK9e0ksnDnxhVnkmpo6dJZu8NZRH0vUQgUgzOWzO++KLcw+gTOR rOYkt+UA2B24ipAsKoIYwPNGve9tqaDro6wk2xyNBGvvW02dtxmZJIA3AfUGSOrsUB9M CnMBcXNMzayB16wGq8otNT6JerPOpYQzTr6BGShkHWLPSM6voIfF5Yg5RqsU87kYeXUy HIu/qoZBVSMrabanLv2q00XVWngsylhL6uGoo5rferFhTToXOVkK8xn6micrPvfnSc1D xvSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791994677; x=1792599477; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=oGTWqBG9/pmcsFuKv5MXNPnEB5Ld1efa93sWaiCHZ/Q=; b=AdKPttRnvYo48tyVIVWcO+U5eijHQoJ/qHKbtqPYjUT350YxdgD8JYkEk+rG3DnRy/ /dkPQq5maY4/2YfocoS3RJUuVlgLscZa758CAQHyU40AkXMNnUMKwwDxcmP/4LaJhcCU j+dXJpIqYwhNA3vFSA6oMv0IOBP2/hjyn1ksKtolIoKkiqRiofLtysY4/Q0HofMEg9rI CWZuJ4otxvIA3kQihb92KoZpHRj7PJrEW5Vtycy2+TR8fCsOiShiCOcwXGEB+yNj2hIG amfAeNSnbZFd5KlRFt7Sl//Lpi+oqnnjyBMPg7DHoWkm1XSDIFSbH+uuLsMW9aWTnXxQ MSkg== X-Forwarded-Encrypted: i=1; AKwUvBzrlhjyGi7S4LpmxWghwRpTEWVxXWGcukeHYnGbkX2Mchbu2TtVN5JYl3MIWenIrLR6mnbv0Cg=@vger.kernel.org X-Gm-Message-State: AFq9FYINOXIM+97/YdGe+mmyhk0uGcy+EGA3f/rytRTD6AQKpSx4oLRA o+hkkM6K9fygTLT2mBXBfzB6UqGUmhpEEJPmHHNl0QqYe3gIPprFnl/Vd6ESRvmNsr1mvEnD6sH xOva4yiPsR66PrGDi7zl1jcOyKQ== X-Received: from dybsi13.prod.google.com ([2002:a05:7301:488d:b0:351:4e46:12d1]) (user=almasrymina job=prod-delivery.src-stubby-dispatcher) by 2002:a05:693c:2806:b0:353:7f17:4358 with SMTP id 5a478bee46e88-3537f174c08mr19838559eec.24.1791994676658; Wed, 14 Oct 2026 09:17:56 -0700 (PDT) Date: Wed, 14 Oct 2026 16:17:51 +0000 In-Reply-To: <20261014161754.3782346-1-almasrymina@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20261014161754.3782346-1-almasrymina@google.com> X-Mailer: git-send-email 2.56.0.176.g3575e65682-goog Message-ID: <20261014161754.3782346-2-almasrymina@google.com> Subject: [PATCH net v3 1/4] net: devmem: unmap dma_buf synchronously on queue uninstall From: Mina Almasry To: Jakub Kicinski , Mina Almasry , Pavel Begunkov , David Wei , Stanislav Fomichev , Taehee Yoo , Paolo Abeni , Kaiyuan Zhang , Bobby Eshleman , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Simon Horman , Shuah Khan , Sumit Semwal , "=?UTF-8?q?Christian=20K=C3=B6nig?=" , Daniel Borkmann , Nikolay Aleksandrov , Tariq Toukan , Kaifeng Wang , Dragos Tatulea Content-Type: text/plain; charset="UTF-8" When a bound net_device is unregistered while userspace still holds a netlink or TCP socket reference on a devmem binding, mp_dmabuf_devmem_uninstall() clears binding->dev to NULL so netdev_nl_sock_priv_destroy() will not touch the unregistered net_device, but leaves the dma_buf attachment mapped until __net_devmem_dmabuf_binding_free() runs later on socket close. Because dma_buf_attach() does not take a reference on dma_dev, device removal frees dma_dev while the attachment is still mapped. Closing the netlink socket afterwards triggers a slab use-after-free in dma_unmap_sg_attrs(): BUG: KASAN: slab-use-after-free in dma_unmap_sg_attrs+0x76/0x2b0 Read of size 8 at addr ffff88810fae64b0 by task kworker/3:1/53 Workqueue: events __net_devmem_dmabuf_binding_free Call Trace: dma_unmap_sg_attrs+0x76/0x2b0 unmap_udmabuf+0x8e/0x100 dma_buf_unmap_attachment+0x145/0x330 dma_buf_unmap_attachment_unlocked+0x96/0x130 __net_devmem_dmabuf_binding_free+0x156/0x2e0 Freed by task 9: kfree+0x1b8/0x550 nsim_bus_dev_release+0xe/0x60 device_release+0xcf/0x250 Add net_devmem_dmabuf_binding_unmap() serialized under binding->lock and null out binding->sgt and binding->attachment after unmapping so unmapping is idempotent across queue uninstall and deferred binding destruction. Call it synchronously when the last bound RX queue is uninstalled in mp_dmabuf_devmem_uninstall(), except when a leased queue is unleased: the physical device is still registered and, if restarting its queue failed, may still be using the binding. The same use-after-free happens when the netlink socket is closed before the device is removed but RX tokens or the pending release work keep the binding alive. Such bindings are no longer installed on any queue and were already erased from net_devmem_dmabuf_bindings. Keep bindings in net_devmem_dmabuf_bindings until they are freed, hide unbound ones from TX lookups with an xarray mark, and on NETDEV_UNREGISTER clear binding->dev of unbound RX bindings for the device and unmap them, unless the device is a virtual device leasing queues, for the same reason as above. The walk runs under the netdev instance lock, so it cannot clear binding->dev while net_devmem_unbind_dmabuf() is still closing queues, and under net_devmem_lock, which serializes it with the final free. It is skipped when the device only moves to another netns. Fixes: f8350a4358fc ("net: page_pool: add a mp hook to unregister_netdevice*") Fixes: 0afc44d8cdf6 ("net: devmem: fix kernel panic when netlink socket close after module unload") Cc: Taehee Yoo Cc: Stanislav Fomichev Cc: Tariq Toukan Cc: Kaifeng Wang Assisted-by: LLM Signed-off-by: Mina Almasry Reviewed-by: Dragos Tatulea --- v3: - Run the NETDEV_UNREGISTER walk under the netdev instance lock so it cannot race with net_devmem_unbind_dmabuf() (Sashiko). - Skip the walk when the device only moves to another netns (Sashiko). v2: - Don't unmap when a leased queue is unleased (Sashiko). - Unmap unbound RX bindings on NETDEV_UNREGISTER; keep bindings in net_devmem_dmabuf_bindings until freed, hidden from TX lookups by NET_DEVMEM_BINDING_LIVE (Sashiko). - Update the binding->lock and binding->ref comments (Sashiko). --- net/core/devmem.c | 92 +++++++++++++++++++++++++++++++++++------- net/core/devmem.h | 10 ++++- net/core/netdev-genl.c | 1 + 3 files changed, 86 insertions(+), 17 deletions(-) diff --git a/net/core/devmem.c b/net/core/devmem.c index f4d60654ce7fd..93cc2815d935a 100644 --- a/net/core/devmem.c +++ b/net/core/devmem.c @@ -20,6 +20,7 @@ #include #include +#include "dev.h" #include "devmem.h" #include "mp_dmabuf_devmem.h" #include "page_pool_priv.h" @@ -27,6 +28,8 @@ /* Device memory support */ static DEFINE_XARRAY_FLAGS(net_devmem_dmabuf_bindings, XA_FLAGS_ALLOC1); +#define NET_DEVMEM_BINDING_LIVE XA_MARK_1 +static DEFINE_MUTEX(net_devmem_lock); static const struct memory_provider_ops dmabuf_devmem_ops; @@ -58,6 +61,21 @@ static void net_devmem_dmabuf_binding_release(struct percpu_ref *ref) schedule_work(&binding->unbind_w); } +static void +net_devmem_dmabuf_binding_unmap(struct net_devmem_dmabuf_binding *binding) +{ + lockdep_assert_held(&binding->lock); + + if (!binding->sgt) + return; + + dma_buf_unmap_attachment_unlocked(binding->attachment, binding->sgt, + binding->direction); + dma_buf_detach(binding->dmabuf, binding->attachment); + binding->sgt = NULL; + binding->attachment = NULL; +} + void __net_devmem_dmabuf_binding_free(struct work_struct *wq) { struct net_devmem_dmabuf_binding *binding = container_of(wq, typeof(*binding), unbind_w); @@ -74,9 +92,13 @@ void __net_devmem_dmabuf_binding_free(struct work_struct *wq) size, avail)) gen_pool_destroy(binding->chunk_pool); - dma_buf_unmap_attachment_unlocked(binding->attachment, binding->sgt, - binding->direction); - dma_buf_detach(binding->dmabuf, binding->attachment); + mutex_lock(&net_devmem_lock); + mutex_lock(&binding->lock); + net_devmem_dmabuf_binding_unmap(binding); + mutex_unlock(&binding->lock); + xa_erase(&net_devmem_dmabuf_bindings, binding->id); + mutex_unlock(&net_devmem_lock); + dma_buf_put(binding->dmabuf); xa_destroy(&binding->bound_rxqs); percpu_ref_exit(&binding->ref); @@ -129,10 +151,11 @@ void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding) unsigned long xa_idx; unsigned int rxq_idx; - xa_erase(&net_devmem_dmabuf_bindings, binding->id); + xa_clear_mark(&net_devmem_dmabuf_bindings, binding->id, + NET_DEVMEM_BINDING_LIVE); /* Ensure no tx net_devmem_lookup_dmabuf() are in flight after the - * erase. + * mark is cleared. */ synchronize_net(); @@ -153,6 +176,38 @@ void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding) percpu_ref_kill(&binding->ref); } +static void +net_devmem_dev_unregister_rx(struct net_devmem_dmabuf_binding *binding, + unsigned long xa_idx, struct net_device *dev) +{ + if (xa_get_mark(&net_devmem_dmabuf_bindings, xa_idx, + NET_DEVMEM_BINDING_LIVE) || + READ_ONCE(binding->dev) != dev) + return; + + mutex_lock(&binding->lock); + WRITE_ONCE(binding->dev, NULL); + if (!netif_is_queue_leasee(dev)) + net_devmem_dmabuf_binding_unmap(binding); + mutex_unlock(&binding->lock); +} + +void net_devmem_dev_unregister(struct net_device *dev) +{ + struct net_devmem_dmabuf_binding *binding; + unsigned long xa_idx; + + if (dev->reg_state != NETREG_UNREGISTERING) + return; + + mutex_lock(&net_devmem_lock); + xa_for_each(&net_devmem_dmabuf_bindings, xa_idx, binding) { + if (binding->direction == DMA_FROM_DEVICE) + net_devmem_dev_unregister_rx(binding, xa_idx, dev); + } + mutex_unlock(&net_devmem_lock); +} + int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx, struct net_devmem_dmabuf_binding *binding, struct netlink_ext_ack *extack) @@ -331,6 +386,8 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, GFP_KERNEL); if (err < 0) goto err_free_chunks; + xa_set_mark(&net_devmem_dmabuf_bindings, binding->id, + NET_DEVMEM_BINDING_LIVE); list_add(&binding->list, &priv->bindings); @@ -359,9 +416,11 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id) { struct net_devmem_dmabuf_binding *binding; + unsigned long xa_idx = id; rcu_read_lock(); - binding = xa_load(&net_devmem_dmabuf_bindings, id); + binding = xa_find(&net_devmem_dmabuf_bindings, &xa_idx, id, + NET_DEVMEM_BINDING_LIVE); if (binding) { if (!net_devmem_dmabuf_binding_get(binding)) binding = NULL; @@ -529,16 +588,19 @@ static void mp_dmabuf_devmem_uninstall(void *mp_priv, unsigned long xa_idx; xa_for_each(&binding->bound_rxqs, xa_idx, bound_rxq) { - if (bound_rxq == rxq) { - xa_erase(&binding->bound_rxqs, xa_idx); - if (xa_empty(&binding->bound_rxqs)) { - mutex_lock(&binding->lock); - ASSERT_EXCLUSIVE_WRITER(binding->dev); - WRITE_ONCE(binding->dev, NULL); - mutex_unlock(&binding->lock); - } - break; + if (bound_rxq != rxq) + continue; + + xa_erase(&binding->bound_rxqs, xa_idx); + if (xa_empty(&binding->bound_rxqs)) { + mutex_lock(&binding->lock); + ASSERT_EXCLUSIVE_WRITER(binding->dev); + WRITE_ONCE(binding->dev, NULL); + if (!rxq->lease) + net_devmem_dmabuf_binding_unmap(binding); + mutex_unlock(&binding->lock); } + break; } } diff --git a/net/core/devmem.h b/net/core/devmem.h index 4a293a7d1149c..5c47c8c3c7d2d 100644 --- a/net/core/devmem.h +++ b/net/core/devmem.h @@ -27,7 +27,7 @@ struct net_devmem_dmabuf_binding { */ void *vdev; struct gen_pool *chunk_pool; - /* Protect dev */ + /* Protect dev, attachment and sgt */ struct mutex lock; /* The user holds a ref (via the netlink API) for as long as they want @@ -38,7 +38,8 @@ struct net_devmem_dmabuf_binding { * * The binding undos itself and unmaps the underlying dmabuf once all * those refs are dropped and the binding is no longer desired or in - * use. + * use. The dmabuf may be unmapped earlier, when the device it is + * mapped for is unregistered. * * net_devmem_get_net_iov() on dmabuf net_iovs will increment this * reference, making sure that the binding remains alive until all the @@ -100,6 +101,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, struct netlink_ext_ack *extack); struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id); void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding); +void net_devmem_dev_unregister(struct net_device *dev); int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx, struct net_devmem_dmabuf_binding *binding, struct netlink_ext_ack *extack); @@ -196,6 +198,10 @@ net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding) { } +static inline void net_devmem_dev_unregister(struct net_device *dev) +{ +} + static inline int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx, struct net_devmem_dmabuf_binding *binding, diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c index 33b9f4eb9565a..b04e22937b789 100644 --- a/net/core/netdev-genl.c +++ b/net/core/netdev-genl.c @@ -1488,6 +1488,7 @@ static int netdev_genl_netdevice_event(struct notifier_block *nb, break; case NETDEV_UNREGISTER: netdev_lock(netdev); + net_devmem_dev_unregister(netdev); netdev_genl_dev_notify(netdev, NETDEV_CMD_DEV_DEL_NTF); netdev_unlock(netdev); break; -- 2.56.0.176.g3575e65682-goog