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Tsirkin" , Jakub Staron , virtualization@lists.linux.dev, nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, Li Chen Subject: [PATCH v3 3/5] nvdimm: virtio_pmem: refcount requests for token lifetime Date: Thu, 26 Feb 2026 10:57:08 +0800 Message-ID: <20260226025712.2236279-4-me@linux.beauty> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260226025712.2236279-1-me@linux.beauty> References: <20260226025712.2236279-1-me@linux.beauty> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMailClient: External Content-Type: text/plain; charset="utf-8" KASAN reports slab-use-after-free in __wake_up_common(): BUG: KASAN: slab-use-after-free in __wake_up_common+0x114/0x160 Read of size 8 at addr ffff88810fdcb710 by task swapper/0/0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.19.0-next-20260220-00006-g1eae5f204ec3 #4 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.17.0-2-2 04/01/2014 Call Trace: dump_stack_lvl+0x6d/0xb0 print_report+0x170/0x4e2 ? __pfx__raw_spin_lock_irqsave+0x10/0x10 ? __virt_addr_valid+0x1dc/0x380 kasan_report+0xbc/0xf0 ? __wake_up_common+0x114/0x160 ? __wake_up_common+0x114/0x160 __wake_up_common+0x114/0x160 ? __pfx__raw_spin_lock_irqsave+0x10/0x10 __wake_up+0x36/0x60 virtio_pmem_host_ack+0x11d/0x3b0 ? sched_balance_domains+0x29f/0xb00 ? __pfx_virtio_pmem_host_ack+0x10/0x10 ? _raw_spin_lock_irqsave+0x98/0x100 ? __pfx__raw_spin_lock_irqsave+0x10/0x10 vring_interrupt+0x1c9/0x5e0 ? __pfx_vp_interrupt+0x10/0x10 vp_vring_interrupt+0x87/0x100 ? __pfx_vp_interrupt+0x10/0x10 __handle_irq_event_percpu+0x17f/0x550 ? __pfx__raw_spin_lock+0x10/0x10 handle_irq_event+0xab/0x1c0 handle_fasteoi_irq+0x276/0xae0 __common_interrupt+0x65/0x130 common_interrupt+0x78/0xa0 virtio_pmem_host_ack() wakes a request that has already been freed by the submitter. This happens when the request token is still reachable via the virtqueue, but virtio_pmem_flush() returns and frees it. Fix the token lifetime by refcounting struct virtio_pmem_request. virtio_pmem_flush() holds a submitter reference, and the virtqueue holds an extra reference once the request is queued. The completion path drops the virtqueue reference, and the submitter drops its reference before returning. Fixes: 6e84200c0a29 ("virtio-pmem: Add virtio pmem driver") Cc: stable@vger.kernel.org Signed-off-by: Li Chen --- v2->v3: - Add raw KASAN report to the patch description. drivers/nvdimm/nd_virtio.c | 34 +++++++++++++++++++++++++++++----- drivers/nvdimm/virtio_pmem.h | 2 ++ 2 files changed, 31 insertions(+), 5 deletions(-) diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c index ada0c679cf2e..d0bf213d8caf 100644 --- a/drivers/nvdimm/nd_virtio.c +++ b/drivers/nvdimm/nd_virtio.c @@ -9,6 +9,14 @@ #include "virtio_pmem.h" #include "nd.h" =20 +static void virtio_pmem_req_release(struct kref *kref) +{ + struct virtio_pmem_request *req; + + req =3D container_of(kref, struct virtio_pmem_request, kref); + kfree(req); +} + static void virtio_pmem_wake_one_waiter(struct virtio_pmem *vpmem) { struct virtio_pmem_request *req_buf; @@ -36,6 +44,7 @@ void virtio_pmem_host_ack(struct virtqueue *vq) virtio_pmem_wake_one_waiter(vpmem); WRITE_ONCE(req_data->done, true); wake_up(&req_data->host_acked); + kref_put(&req_data->kref, virtio_pmem_req_release); } spin_unlock_irqrestore(&vpmem->pmem_lock, flags); } @@ -66,6 +75,7 @@ static int virtio_pmem_flush(struct nd_region *nd_region) if (!req_data) return -ENOMEM; =20 + kref_init(&req_data->kref); WRITE_ONCE(req_data->done, false); init_waitqueue_head(&req_data->host_acked); init_waitqueue_head(&req_data->wq_buf); @@ -83,10 +93,23 @@ static int virtio_pmem_flush(struct nd_region *nd_regio= n) * to req_list and wait for host_ack to wake us up when free * slots are available. */ - while ((err =3D virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req_data, - GFP_ATOMIC)) =3D=3D -ENOSPC) { - - dev_info(&vdev->dev, "failed to send command to virtio pmem device, no f= ree slots in the virtqueue\n"); + for (;;) { + err =3D virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req_data, + GFP_ATOMIC); + if (!err) { + /* + * Take the virtqueue reference while @pmem_lock is + * held so completion cannot run concurrently. + */ + kref_get(&req_data->kref); + break; + } + + if (err !=3D -ENOSPC) + break; + + dev_info_ratelimited(&vdev->dev, + "failed to send command to virtio pmem device, no free slots in t= he virtqueue\n"); WRITE_ONCE(req_data->wq_buf_avail, false); list_add_tail(&req_data->list, &vpmem->req_list); spin_unlock_irqrestore(&vpmem->pmem_lock, flags); @@ -95,6 +118,7 @@ static int virtio_pmem_flush(struct nd_region *nd_region) wait_event(req_data->wq_buf, READ_ONCE(req_data->wq_buf_avail)); spin_lock_irqsave(&vpmem->pmem_lock, flags); } + err1 =3D virtqueue_kick(vpmem->req_vq); spin_unlock_irqrestore(&vpmem->pmem_lock, flags); /* @@ -110,7 +134,7 @@ static int virtio_pmem_flush(struct nd_region *nd_regio= n) err =3D le32_to_cpu(req_data->resp.ret); } =20 - kfree(req_data); + kref_put(&req_data->kref, virtio_pmem_req_release); return err; }; =20 diff --git a/drivers/nvdimm/virtio_pmem.h b/drivers/nvdimm/virtio_pmem.h index f72cf17f9518..1017e498c9b4 100644 --- a/drivers/nvdimm/virtio_pmem.h +++ b/drivers/nvdimm/virtio_pmem.h @@ -12,11 +12,13 @@ =20 #include #include +#include #include #include #include =20 struct virtio_pmem_request { + struct kref kref; struct virtio_pmem_req req; struct virtio_pmem_resp resp; =20 --=20 2.52.0