net/sched: cls_fw: Fix improper refcount update leads to use-after-free
commit 0323bce5 upstream. In the event of a failure in tcf_change_indev(), fw_set_parms() will immediately return an error after incrementing or decrementing reference counter in tcf_bind_filter(). If attacker can control reference counter to zero and make reference freed, leading to use after free. In order to prevent this, move the point of possible failure above the point where the TC_FW_CLASSID is handled. Fixes: 1da177e4 ("Linux-2.6.12-rc2") Reported-by: M A Ramdhan <ramdhan@starlabs.sg> Signed-off-by: M A Ramdhan <ramdhan@starlabs.sg> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Reviewed-by: Pedro Tammela <pctammela@mojatatu.com> Message-ID: <20230705161530.52003-1-ramdhan@starlabs.sg> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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a4b97824
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