This is ported from Dave Marchevsky's patch [0], which is needed for the bpf iterators callback to return values beyond the 0, 1 range. For comments, please refer to Dave's patch. [0] https://lore.kernel.org/bpf/20220830172759.4069786-2-davemarchevsky@xxxxxx/ Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx> --- include/linux/bpf_verifier.h | 1 + kernel/bpf/verifier.c | 5 +++-- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 8fbc1d05281e..63cda732ee10 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -248,6 +248,7 @@ struct bpf_func_state { */ u32 async_entry_cnt; bool in_callback_fn; + struct tnum callback_ret_range; bool in_async_callback_fn; /* The following fields should be last. See copy_func_state() */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8c8c101513f5..2eb2a4410344 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1814,6 +1814,7 @@ static void init_func_state(struct bpf_verifier_env *env, state->callsite = callsite; state->frameno = frameno; state->subprogno = subprogno; + state->callback_ret_range = tnum_range(0, 1); init_reg_state(env, state); mark_verifier_state_scratched(env); } @@ -6974,6 +6975,7 @@ static int set_find_vma_callback_state(struct bpf_verifier_env *env, __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); return 0; } @@ -7000,8 +7002,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) state->curframe--; caller = state->frame[state->curframe]; if (callee->in_callback_fn) { - /* enforce R0 return value range [0, 1]. */ - struct tnum range = tnum_range(0, 1); + struct tnum range = callee->callback_ret_range; if (r0->type != SCALAR_VALUE) { verbose(env, "R0 not a scalar value\n"); -- 2.30.2
