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From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 19 Nov 2022 18:48:42 +0100
Subject: [PATCH] netfilter: nf_flow_table: 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
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/net/netfilter/nf_flow_table_offload.c
+++ b/net/netfilter/nf_flow_table_offload.c
@@ -1074,6 +1074,7 @@ static int nf_flow_table_block_setup(str
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);
@@ -1088,6 +1089,7 @@ static int nf_flow_table_block_setup(str
WARN_ON_ONCE(1);
err = -EOPNOTSUPP;
}
+ up_write(&flowtable->flow_block_lock);
return err;
}
@@ -1144,7 +1146,9 @@ static int nf_flow_table_offload_cmd(str
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;
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