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:
<IRQ>
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
</IRQ>
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: [email protected]
Signed-off-by: Li Chen <[email protected]>
---
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"
+static void virtio_pmem_req_release(struct kref *kref)
+{
+ struct virtio_pmem_request *req;
+
+ req = 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;
+ 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_region)
* to req_list and wait for host_ack to wake us up when free
* slots are available.
*/
- while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req_data,
- GFP_ATOMIC)) == -ENOSPC) {
-
- dev_info(&vdev->dev, "failed to send command to virtio pmem
device, no free slots in the virtqueue\n");
+ for (;;) {
+ err = 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 != -ENOSPC)
+ break;
+
+ dev_info_ratelimited(&vdev->dev,
+ "failed to send command to virtio pmem
device, no free slots in the 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 = 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_region)
err = le32_to_cpu(req_data->resp.ret);
}
- kfree(req_data);
+ kref_put(&req_data->kref, virtio_pmem_req_release);
return err;
};
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 @@
#include <linux/module.h>
#include <uapi/linux/virtio_pmem.h>
+#include <linux/kref.h>
#include <linux/libnvdimm.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
struct virtio_pmem_request {
+ struct kref kref;
struct virtio_pmem_req req;
struct virtio_pmem_resp resp;
--
2.52.0
