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Subject[PATCH 4.20 090/183] xsk: Check if a queue exists during umem setup
4.20-stable review patch.  If anyone has any objections, please let me know.


[ Upstream commit cc5b5d3565048ae57d14e5674a5fb085b2ab0193 ]

In the xdp_umem_assign_dev() path, the xsk code does not
check if a queue for which umem is to be created exists.
It leads to a situation where umem is not assigned to any
Tx/Rx queue of a netdevice, without notifying the stack
about an error. This affects both XDP_SKB and XDP_DRV
modes - in case of XDP_DRV_ZC, queue index is checked by
the driver.

This patch fixes xsk code, so that in both XDP_SKB and
XDP_DRV mode of AF_XDP, an error is returned when requested
queue index exceedes an existing maximum.

Fixes: c9b47cc1fabca ("xsk: fix bug when trying to use both copy and zero-copy on one queue id")
Reported-by: Jakub Spizewski <>
Signed-off-by: Krzysztof Kazimierczak <>
Acked-by: Björn Töpel <>
Signed-off-by: Daniel Borkmann <>
Signed-off-by: Sasha Levin <>
net/xdp/xdp_umem.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index a264cf2accd0f..d4de871e7d4d7 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -41,13 +41,20 @@ void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
* not know if the device has more tx queues than rx, or the opposite.
* This might also change during run time.
-static void xdp_reg_umem_at_qid(struct net_device *dev, struct xdp_umem *umem,
- u16 queue_id)
+static int xdp_reg_umem_at_qid(struct net_device *dev, struct xdp_umem *umem,
+ u16 queue_id)
+ if (queue_id >= max_t(unsigned int,
+ dev->real_num_rx_queues,
+ dev->real_num_tx_queues))
+ return -EINVAL;
if (queue_id < dev->real_num_rx_queues)
dev->_rx[queue_id].umem = umem;
if (queue_id < dev->real_num_tx_queues)
dev->_tx[queue_id].umem = umem;
+ return 0;

struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev,
@@ -88,7 +95,10 @@ int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
goto out_rtnl_unlock;

- xdp_reg_umem_at_qid(dev, umem, queue_id);
+ err = xdp_reg_umem_at_qid(dev, umem, queue_id);
+ if (err)
+ goto out_rtnl_unlock;
umem->dev = dev;
umem->queue_id = queue_id;
if (force_copy)

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