From patchwork Thu Oct 29 22:09:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Rogers X-Patchwork-Id: 316019 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93D1EC2D0A3 for ; Thu, 29 Oct 2020 22:09:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16EB42075E for ; Thu, 29 Oct 2020 22:09:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="iJd8+tQg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725379AbgJ2WJ1 (ORCPT ); Thu, 29 Oct 2020 18:09:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725372AbgJ2WJ0 (ORCPT ); Thu, 29 Oct 2020 18:09:26 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BF9AC0613D2 for ; Thu, 29 Oct 2020 15:09:26 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id q8so4197145ybk.18 for ; Thu, 29 Oct 2020 15:09:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:message-id:mime-version:subject:from:to:cc; bh=1cM6j3pKkngnTbCX3y8IdmZDWyWruLHgBjGmPp/ecPk=; b=iJd8+tQgBnYM/lmhDcjsMUy7GHqZGButn+ucz/xowxFTnUuOEFw53/5q+BjNufNaVv 1y4KdC8+NqbEo7u3HDm3pLM0bHbAGdJJBp7JfFxT4uGu6T0vWcvBbnKE6soQsZ20WDkr bNjGGQD+0C0uXWgBLSdFl81nyuaa+f1NEJTxeA2HDU+3UdHi9jQM65PfDfq8dLHbnJeN qMb58Xb9Dcp/I3iL2MiwE85Oo1RvqJZgJyQ8v0BK//cj8eBy3IKpwhFYSUj6fxndEkv9 Dhwb2BzJ64b4aModvvGFO36XVjlteRRX/AD3/qq/020Uanc8QQGD1S6IEYXm7mTlGwgh rs/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:message-id:mime-version:subject:from :to:cc; bh=1cM6j3pKkngnTbCX3y8IdmZDWyWruLHgBjGmPp/ecPk=; b=ISuR5OhSiBGUDqNOd+jWWpYs8+1FUFEODuACnY6dkxvCGNtB2nW+K+irJx20/QiUNe vlc4gMeeCcKovL8ExRAMChA54xqenvKWpmNFt91oVFZtvbkLBuH1rr5QIAk8JeNO8mMz XfXr0LogODqnQyJhVCxmT8/gLwup39QBECIPTkzOIjhB0QfQUH1Iwry5i873U0K8JsMD Kawtp2u8o+3XaOKzV39RLYWMrpu9BCnsyC6ZbOeVrQ2Y+FkXep8oWf4T8+rKLXw52eOq q1MxMIs4ZwgKggONXAFnw1+27W94wBmaQnLPxbWJ6AeUZ5gPGtPInCDeGt634sNFAb5z I26w== X-Gm-Message-State: AOAM531OMfB4PG0HeyQLXRekvODm7OoC92ihKwtRyeTViaqu8wS0y9Wc G0KoEGCu8QCSsWD40SU7dxzVBBSxu6e2 X-Google-Smtp-Source: ABdhPJzADNuhOKyKxFcG37Lep6XsfQ5pKWZYgCHXVwIYTS/EuifKeuinSSnF1r4Zxn+2uk6ZrWXjHkN0gL7/ Sender: "irogers via sendgmr" X-Received: from irogers.svl.corp.google.com ([2620:15c:2cd:2:f693:9fff:fef4:4583]) (user=irogers job=sendgmr) by 2002:a25:d8a:: with SMTP id 132mr9311332ybn.7.1604009365495; Thu, 29 Oct 2020 15:09:25 -0700 (PDT) Date: Thu, 29 Oct 2020 15:09:19 -0700 Message-Id: <20201029220919.481279-1-irogers@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.29.1.341.ge80a0c044ae-goog Subject: [PATCH] libbpf hashmap: Avoid undefined behavior in hash_bits From: Ian Rogers To: Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Ian Rogers Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org If bits is 0, the case when the map is empty, then the >> is the size of the register which is undefined behavior - on x86 it is the same as a shift by 0. Avoid calling hash_bits with bits == 0 by adding additional empty hashmap tests. Suggested-by: Andrii Nakryiko , Suggested-by: Song Liu Signed-off-by: Ian Rogers --- tools/lib/bpf/hashmap.c | 12 ++++++++++-- tools/lib/bpf/hashmap.h | 12 ++++++------ 2 files changed, 16 insertions(+), 8 deletions(-) diff --git a/tools/lib/bpf/hashmap.c b/tools/lib/bpf/hashmap.c index 3c20b126d60d..41e6f636101e 100644 --- a/tools/lib/bpf/hashmap.c +++ b/tools/lib/bpf/hashmap.c @@ -156,7 +156,7 @@ int hashmap__insert(struct hashmap *map, const void *key, void *value, const void **old_key, void **old_value) { struct hashmap_entry *entry; - size_t h; + size_t h = 0; int err; if (old_key) @@ -164,7 +164,9 @@ int hashmap__insert(struct hashmap *map, const void *key, void *value, if (old_value) *old_value = NULL; - h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); + if (map->buckets) + h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); + if (strategy != HASHMAP_APPEND && hashmap_find_entry(map, key, h, NULL, &entry)) { if (old_key) @@ -208,6 +210,9 @@ bool hashmap__find(const struct hashmap *map, const void *key, void **value) struct hashmap_entry *entry; size_t h; + if (!map->buckets) + return false; + h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); if (!hashmap_find_entry(map, key, h, NULL, &entry)) return false; @@ -223,6 +228,9 @@ bool hashmap__delete(struct hashmap *map, const void *key, struct hashmap_entry **pprev, *entry; size_t h; + if (!map->buckets) + return false; + h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); if (!hashmap_find_entry(map, key, h, &pprev, &entry)) return false; diff --git a/tools/lib/bpf/hashmap.h b/tools/lib/bpf/hashmap.h index d9b385fe808c..61236437876e 100644 --- a/tools/lib/bpf/hashmap.h +++ b/tools/lib/bpf/hashmap.h @@ -174,17 +174,17 @@ bool hashmap__find(const struct hashmap *map, const void *key, void **value); * @key: key to iterate entries for */ #define hashmap__for_each_key_entry(map, cur, _key) \ - for (cur = ({ size_t bkt = hash_bits(map->hash_fn((_key), map->ctx),\ - map->cap_bits); \ - map->buckets ? map->buckets[bkt] : NULL; }); \ + for (cur = map->buckets \ + ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \ + : NULL; \ cur; \ cur = cur->next) \ if (map->equal_fn(cur->key, (_key), map->ctx)) #define hashmap__for_each_key_entry_safe(map, cur, tmp, _key) \ - for (cur = ({ size_t bkt = hash_bits(map->hash_fn((_key), map->ctx),\ - map->cap_bits); \ - cur = map->buckets ? map->buckets[bkt] : NULL; }); \ + for (cur = map->buckets \ + ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \ + : NULL; \ cur && ({ tmp = cur->next; true; }); \ cur = tmp) \ if (map->equal_fn(cur->key, (_key), map->ctx))