From 4f73379ec5c2891598aa715c6df7ac9afdc86fbf Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 1 Apr 2019 21:27:44 -0700 Subject: bpf: verbose jump offset overflow check Larger programs may trigger 16-bit jump offset overflow check during instruction patching. Make this error verbose otherwise users cannot decipher error code without printks in the verifier. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- kernel/bpf/core.c | 11 ++++++----- kernel/bpf/verifier.c | 7 ++++++- 2 files changed, 12 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index ff09d32a8a1b..2966cb368bf4 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -438,6 +438,7 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, u32 insn_adj_cnt, insn_rest, insn_delta = len - 1; const u32 cnt_max = S16_MAX; struct bpf_prog *prog_adj; + int err; /* Since our patchlet doesn't expand the image, we're done. */ if (insn_delta == 0) { @@ -453,8 +454,8 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, * we afterwards may not fail anymore. */ if (insn_adj_cnt > cnt_max && - bpf_adj_branches(prog, off, off + 1, off + len, true)) - return NULL; + (err = bpf_adj_branches(prog, off, off + 1, off + len, true))) + return ERR_PTR(err); /* Several new instructions need to be inserted. Make room * for them. Likely, there's no need for a new allocation as @@ -463,7 +464,7 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, prog_adj = bpf_prog_realloc(prog, bpf_prog_size(insn_adj_cnt), GFP_USER); if (!prog_adj) - return NULL; + return ERR_PTR(-ENOMEM); prog_adj->len = insn_adj_cnt; @@ -1096,13 +1097,13 @@ struct bpf_prog *bpf_jit_blind_constants(struct bpf_prog *prog) continue; tmp = bpf_patch_insn_single(clone, i, insn_buff, rewritten); - if (!tmp) { + if (IS_ERR(tmp)) { /* Patching may have repointed aux->prog during * realloc from the original one, so we need to * fix it up here on error. */ bpf_jit_prog_release_other(prog, clone); - return ERR_PTR(-ENOMEM); + return tmp; } clone = tmp; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ad3494a881da..6dcfeb44bb8e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6932,8 +6932,13 @@ static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 of struct bpf_prog *new_prog; new_prog = bpf_patch_insn_single(env->prog, off, patch, len); - if (!new_prog) + if (IS_ERR(new_prog)) { + if (PTR_ERR(new_prog) == -ERANGE) + verbose(env, + "insn %d cannot be patched due to 16-bit range\n", + env->insn_aux_data[off].orig_idx); return NULL; + } if (adjust_insn_aux_data(env, new_prog->len, off, len)) return NULL; adjust_subprog_starts(env, off, len); -- cgit v1.2.3