[net-next,2/3] net: qrtr: ns: Change nodes radix tree to xarray

Commit Message

Vignesh Viswanathan July 12, 2023, 11:26 a.m. UTC

There is a use after free scenario while iterating through the nodes
radix tree despite the ns being a single threaded process. This can
happen when the radix tree APIs are not synchronized with the
rcu_read_lock() APIs.

Convert the radix tree for nodes to xarray to take advantage of the
built in rcu lock usage provided by xarray.

Signed-off-by: Chris Lew <[e-mail]>
Signed-off-by: Vignesh Viswanathan <[e-mail]>
---
 net/qrtr/ns.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Simon Horman July 13, 2023, 2:55 p.m. UTC | #1

On Wed, Jul 12, 2023 at 04:56:30PM +0530, Vignesh Viswanathan wrote:
> There is a use after free scenario while iterating through the nodes
> radix tree despite the ns being a single threaded process. This can
> happen when the radix tree APIs are not synchronized with the
> rcu_read_lock() APIs.
> 
> Convert the radix tree for nodes to xarray to take advantage of the
> built in rcu lock usage provided by xarray.
> 
> Signed-off-by: Chris Lew <[e-mail]>
> Signed-off-by: Vignesh Viswanathan <[e-mail]>

Reviewed-by: Simon Horman <[e-mail]>

Patch

diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
index 039313c3e044..12de671d7992 100644
--- a/net/qrtr/ns.c
+++ b/net/qrtr/ns.c
@@ -16,7 +16,7 @@ 
 #define CREATE_TRACE_POINTS
 #include <trace/events/qrtr.h>
 
-static RADIX_TREE(nodes, GFP_KERNEL);
+static DEFINE_XARRAY(nodes);
 
 static struct {
 	struct socket *sock;
@@ -73,7 +73,7 @@  static struct qrtr_node *node_get(unsigned int node_id)
 {
 	struct qrtr_node *node;
 
-	node = radix_tree_lookup(&nodes, node_id);
+	node = xa_load(&nodes, node_id);
 	if (node)
 		return node;
 
@@ -85,7 +85,7 @@  static struct qrtr_node *node_get(unsigned int node_id)
 	node->id = node_id;
 	xa_init(&node->servers);
 
-	if (radix_tree_insert(&nodes, node_id, node)) {
+	if (xa_store(&nodes, node_id, node, GFP_KERNEL)) {
 		kfree(node);
 		return NULL;
 	}