netfilter: flowtable_offload: add missing locking
nf_flow_table_block_setup and the driver TC_SETUP_FT call can modify the flow
block cb list while they are being traversed elsewhere, causing a crash.
Add a write lock around the calls to protect readers
Fixes: c29f74e0df7a ("netfilter: nf_flow_table: hardware offload support")
Reported-by: Chad Monroe <chad.monroe@smartrg.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_flow_table_offload.c b/net/netfilter/nf_flow_table_offload.c
index b04645c..00b5228 100644
--- a/net/netfilter/nf_flow_table_offload.c
+++ b/net/netfilter/nf_flow_table_offload.c
@@ -1098,6 +1098,7 @@
struct flow_block_cb *block_cb, *next;
int err = 0;
+ down_write(&flowtable->flow_block_lock);
switch (cmd) {
case FLOW_BLOCK_BIND:
list_splice(&bo->cb_list, &flowtable->flow_block.cb_list);
@@ -1112,6 +1113,7 @@
WARN_ON_ONCE(1);
err = -EOPNOTSUPP;
}
+ up_write(&flowtable->flow_block_lock);
return err;
}
@@ -1168,7 +1170,9 @@
nf_flow_table_block_offload_init(bo, dev_net(dev), cmd, flowtable,
extack);
+ down_write(&flowtable->flow_block_lock);
err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_FT, bo);
+ up_write(&flowtable->flow_block_lock);
if (err < 0)
return err;
