Skip to content

bpf: properly verify tail call behavior #6300

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
Closed

bpf: properly verify tail call behavior #6300

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
26 changes: 23 additions & 3 deletions kernel/bpf/verifier.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11005,6 +11005,10 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
bool in_callback_fn;
int err;

err = bpf_update_live_stack(env);
if (err)
return err;

callee = state->frame[state->curframe];
r0 = &callee->regs[BPF_REG_0];
if (r0->type == PTR_TO_STACK) {
Expand Down Expand Up @@ -11911,6 +11915,25 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
env->prog->call_get_func_ip = true;
}

if (func_id == BPF_FUNC_tail_call) {
if (env->cur_state->curframe) {
struct bpf_verifier_state *branch;

mark_reg_scratched(env, BPF_REG_0);
branch = push_stack(env, env->insn_idx + 1, env->insn_idx, false);
if (IS_ERR(branch))
return PTR_ERR(branch);
clear_all_pkt_pointers(env);
mark_reg_unknown(env, regs, BPF_REG_0);
err = prepare_func_exit(env, &env->insn_idx);
if (err)
return err;
env->insn_idx--;
} else {
changes_data = false;
}
}

if (changes_data)
clear_all_pkt_pointers(env);
return 0;
Expand Down Expand Up @@ -19876,9 +19899,6 @@ static int process_bpf_exit_full(struct bpf_verifier_env *env,
return PROCESS_BPF_EXIT;

if (env->cur_state->curframe) {
err = bpf_update_live_stack(env);
if (err)
return err;
/* exit from nested function */
err = prepare_func_exit(env, &env->insn_idx);
if (err)
Expand Down
Loading