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 xps_queue_show+0x469/0x480
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 <aten...@kernel.org>
---
net/core/dev.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 052797ca65f6..748e377c7fe3 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;
@@ -2768,7 +2770,7 @@ int __netif_set_xps_queue(struct net_device *dev, const
unsigned long *mask,
}
}
- kfree_rcu(dev_maps, rcu);
+ old_dev_maps = copy ? dev_maps : NULL;
out_no_old_maps:
dev_maps = new_dev_maps;
@@ -2794,10 +2796,14 @@ 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, old_dev_maps, 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);
--
2.29.2
