[PATCH net-next v4 12/13] net: fix use after free in xps
From: Antoine Tenart <atenart@kernel.org>
Date: 2021-03-18 18:39:27
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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: Antoine Tenart <atenart@kernel.org> --- net/core/dev.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index c8ce2dfcc97d..d5f6ba209f1e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -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);
--
2.30.2