Commit 2d05bf01 authored by Antoine Tenart's avatar Antoine Tenart Committed by David S. Miller
Browse files

net: fix use after free in xps 



When setting up an new dev_maps in __netif_set_xps_queue, we remove and
free maps from unused CPUs/rx-queues near the end of the function; by
calling remove_xps_queue. However it's possible those maps are also part
of the old not-freed-yet dev_maps, which might be used concurrently.
When that happens, a map can be freed while its corresponding entry in
the old dev_maps table isn't NULLed, leading to: "BUG: KASAN:
use-after-free" in different places.

This fixes the map freeing logic for unused CPUs/rx-queues, to also NULL
the map entries from the old dev_maps table.

Signed-off-by: default avatarAntoine Tenart <atenart@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2db6cdae

net/core/dev.c

+12 −5
Original line number Diff line number Diff line
@@ -2460,7 +2460,7 @@ static DEFINE_MUTEX(xps_map_mutex); 
	rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))



static bool remove_xps_queue(struct xps_dev_maps *dev_maps,

			     int tci, u16 index)

			     struct xps_dev_maps *old_maps, int tci, u16 index)

{

	struct xps_map *map = NULL;

	int pos;
@@ -2479,6 +2479,8 @@ static bool remove_xps_queue(struct xps_dev_maps *dev_maps, 
			break;

		}



		if (old_maps)

			RCU_INIT_POINTER(old_maps->attr_map[tci], NULL);

		RCU_INIT_POINTER(dev_maps->attr_map[tci], NULL);

		kfree_rcu(map, rcu);

		return false;
@@ -2499,7 +2501,7 @@ static bool remove_xps_queue_cpu(struct net_device *dev, 
		int i, j;



		for (i = count, j = offset; i--; j++) {

			if (!remove_xps_queue(dev_maps, tci, j))

			if (!remove_xps_queue(dev_maps, NULL, tci, j))

				break;

		}
@@ -2631,7 +2633,7 @@ static void xps_copy_dev_maps(struct xps_dev_maps *dev_maps, 
int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,

			  u16 index, enum xps_map_type type)

{

	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;

	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL, *old_dev_maps = NULL;

	const unsigned long *online_mask = NULL;

	bool active = false, copy = false;

	int i, j, tci, numa_node_id = -2;
@@ -2766,7 +2768,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask, 
		}

	}



	kfree_rcu(dev_maps, rcu);

	old_dev_maps = dev_maps;



out_no_old_maps:

	dev_maps = new_dev_maps;
@@ -2792,10 +2794,15 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask, 
			    netif_attr_test_online(j, online_mask, dev_maps->nr_ids))

				continue;



			active |= remove_xps_queue(dev_maps, tci, index);

			active |= remove_xps_queue(dev_maps,

						   copy ? old_dev_maps : NULL,

						   tci, index);

		}

	}



	if (old_dev_maps)

		kfree_rcu(old_dev_maps, rcu);



	/* free map if not active */

	if (!active)

		reset_xps_maps(dev, dev_maps, type);