Commit f59bbfc2 authored Jan 21, 2020 by Alexei Starovoitov Committed by Daniel Borkmann Jan 22, 2020

bpf: Fix error path under memory pressure

Restore the 'if (env->cur_state)' check that was incorrectly removed during
code move. Under memory pressure env->cur_state can be freed and zeroed inside
do_check(). Hence the check is necessary.

Fixes: 51c39bb1 ("bpf: Introduce function-by-function verification")
Reported-by: <syzbot+b296579ba5015704d9fa@syzkaller.appspotmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200122024138.3385590-1-ast@kernel.org

parent 05d57f17

kernel/bpf/verifier.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -9594,8 +9594,13 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog)

		ret = do_check(env);
		out:
		/* check for NULL is necessary, since cur_state can be freed inside
		* do_check() under memory pressure.
		*/
		if (env->cur_state) {
		free_verifier_state(env->cur_state, true);
		env->cur_state = NULL;
		}
		while (!pop_stack(env, NULL, NULL));
		free_states(env);
		if (ret)