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 <>
Signed-off-by: Felix Fietkau <>
Signed-off-by: Pablo Neira Ayuso <>
1 file changed