diff options
| author | Andrii Nakryiko <[email protected]> | 2023-12-02 09:56:57 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <[email protected]> | 2023-12-02 11:36:50 -0800 |
| commit | 0acd03a5bd188b0c501d285d938439618bd855c4 (patch) | |
| tree | 2922aa43c9b81c4f7925db4abf022cd041f1dcc0 | |
| parent | 5fad52bee30414270104525e3a0266327a6e9d11 (diff) | |
bpf: enforce precision of R0 on callback return
Given verifier checks actual value, r0 has to be precise, so we need to
propagate precision properly. r0 also has to be marked as read,
otherwise subsequent state comparisons will ignore such register as
unimportant and precision won't really help here.
Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper")
Acked-by: Eduard Zingerman <[email protected]>
Acked-by: Shung-Hsi Yu <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
| -rw-r--r-- | kernel/bpf/verifier.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 25b9d470957e..849fbf47b5f3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9590,6 +9590,13 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) verbose(env, "R0 not a scalar value\n"); return -EACCES; } + + /* we are going to rely on register's precise value */ + err = mark_reg_read(env, r0, r0->parent, REG_LIVE_READ64); + err = err ?: mark_chain_precision(env, BPF_REG_0); + if (err) + return err; + if (!tnum_in(range, r0->var_off)) { verbose_invalid_scalar(env, r0, &range, "callback return", "R0"); return -EINVAL; |