From: Alexei Starovoitov Date: Wed, 22 Jan 2020 02:41:38 +0000 (-0800) Subject: bpf: Fix error path under memory pressure X-Git-Tag: v5.10.7~3383^2~46^2~4 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f59bbfc2f6099e8655f9e8f585e10ffde17176d0;p=platform%2Fkernel%2Flinux-rpi.git 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: 51c39bb1d5d1 ("bpf: Introduce function-by-function verification") Reported-by: syzbot+b296579ba5015704d9fa@syzkaller.appspotmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20200122024138.3385590-1-ast@kernel.org --- diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ca17dccc..6defbec9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9594,8 +9594,13 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) ret = do_check(env); out: - free_verifier_state(env->cur_state, true); - env->cur_state = NULL; + /* 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)