netfilter: flowtable_offload: add missing locking

stable inclusion
from stable-v5.10.157
commit b8e494240e69f91517256adcd6fda62d0671772d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7MU59

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b8e494240e69f91517256adcd6fda62d0671772d

--------------------------------

[ Upstream commit bcd9e3c1 ]

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: c29f74e0 ("netfilter: nf_flow_table: hardware offload support")
Reported-by: NChad Monroe <chad.monroe@smartrg.com>
Signed-off-by: NFelix Fietkau <nbd@nbd.name>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nsanglipeng <sanglipeng1@jd.com>

net/netfilter/nf_flow_table_offload.c

@@ -910,6 +910,7 @@ static int nf_flow_table_block_setup(struct nf_flowtable *flowtable,
 	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);
@@ -924,6 +925,7 @@ static int nf_flow_table_block_setup(struct nf_flowtable *flowtable,
 		WARN_ON_ONCE(1);
 		err = -EOPNOTSUPP;
 	}
+	up_write(&flowtable->flow_block_lock);
 
 	return err;
 }
@@ -980,7 +982,9 @@ static int nf_flow_table_offload_cmd(struct flow_block_offload *bo,
 
 	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;