From patchwork Wed Nov 25 17:34:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marco Elver X-Patchwork-Id: 11931971 X-Patchwork-Delegate: kuba@kernel.org 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 A8619C56201 for ; Wed, 25 Nov 2020 17:34:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F7B1206B5 for ; Wed, 25 Nov 2020 17:34:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vdR9GifL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730455AbgKYRev (ORCPT ); Wed, 25 Nov 2020 12:34:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729631AbgKYReu (ORCPT ); Wed, 25 Nov 2020 12:34:50 -0500 Received: from mail-qt1-x849.google.com (mail-qt1-x849.google.com [IPv6:2607:f8b0:4864:20::849]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C7B68C0613D4 for ; Wed, 25 Nov 2020 09:34:50 -0800 (PST) Received: by mail-qt1-x849.google.com with SMTP id a22so2997830qtx.20 for ; Wed, 25 Nov 2020 09:34:50 -0800 (PST) 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=K7k20R0lnhz68i2HIZxX0s22aPKx+LMM7GFJ9tvlIjc=; b=vdR9GifL3hQTkcfJ1FFE918sa3YXXR6ooyED/fdgmlWBC7ugf8qUyt0myBTMWvtBGH uztf9VdHFsQ0r8V+hTwQ+Kr24RmVCMZvBf2RhpI8NpxUjFXYurG8jDkG4hi5v0TQrw3r kWU197AsXlVUEz+u+9yZqSCJnomy6vOY2iwAdTeQxf5la2wEbw299JckjbMJwOsUf8ZH qKYbwZ+D4j4XjrUR5hvUM6XDqHJPUjSTlwAMIEpTZYaJbwA3h9tE7czB2mOQbs30L3tN rCinW5dYyTTMxgHmxvOH9ikXvIhY3Ryugb4At8R7GVh9DE4KwV06S5Tjv8qQ6haezxdu 0JSA== 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=K7k20R0lnhz68i2HIZxX0s22aPKx+LMM7GFJ9tvlIjc=; b=kGxw5JZ7AYUDVNdhhuko32J9m4poy39UtJ1IBy7uHzxdAZ1S96pbiYVfxU3J6vX+W0 mYhLE8WBJjpZvBy3pQa7m1O25B/z4L2vB0Xn8ye/dmNK0DYVWGaXzOBHjjW2jUbaby6f BMvDNPsS+msjl9X3DHNmDtPuBJXVYOeAYt5I7IdVmgzMHhca+oZcnwmYKiFFzO3ofbnk JuM1LYNRrkOa6eYaqyeGvKb8UK3vjMJQ6YTufXM/q4gTufDBbtobLvkw6ajQew+qLH0z 8ODyALINBJEkx4T8ur3u3++QIYo7F7VlLyltIue8YzYl6k9sRLvTKob9qhvTSd48Qo+F aGUw== X-Gm-Message-State: AOAM531TGJeF0WfacSDTceWs6J9UOucRM1atU9LiF848BhUWFz592I2I UkKQVbHE1toiZDTfNcWertofo5dOVg== X-Google-Smtp-Source: ABdhPJy2FeQNFhtN4W83T3gNPR88Jl1wwy7z0LkxjggKG27FXx85OpSWy+xm1c455Nx/l9V3TW8tktq6tg== Sender: "elver via sendgmr" X-Received: from elver.muc.corp.google.com ([2a00:79e0:15:13:f693:9fff:fef4:2449]) (user=elver job=sendgmr) by 2002:a0c:fa4f:: with SMTP id k15mr4267615qvo.62.1606325689848; Wed, 25 Nov 2020 09:34:49 -0800 (PST) Date: Wed, 25 Nov 2020 18:34:36 +0100 Message-Id: <20201125173436.1894624-1-elver@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.29.2.454.gaff20da3a2-goog Subject: [PATCH net-next] net: switch to storing KCOV handle directly in sk_buff From: Marco Elver To: elver@google.com, kuba@kernel.org, davem@davemloft.net Cc: johannes@sipsolutions.net, a.nogikh@gmail.com, andreyknvl@google.com, dvyukov@google.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, idosch@idosch.org, fw@strlen.de, willemb@google.com Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org It turns out that usage of skb extensions can cause memory leaks. Ido Schimmel reported: "[...] there are instances that blindly overwrite 'skb->extensions' by invoking skb_copy_header() after __alloc_skb()." Therefore, give up on using skb extensions for KCOV handle, and instead directly store kcov_handle in sk_buff. Fixes: 6370cc3bbd8a ("net: add kcov handle to skb extensions") Fixes: 85ce50d337d1 ("net: kcov: don't select SKB_EXTENSIONS when there is no NET") Fixes: 97f53a08cba1 ("net: linux/skbuff.h: combine SKB_EXTENSIONS + KCOV handling") Link: https://lore.kernel.org/linux-wireless/20201121160941.GA485907@shredder.lan/ Reported-by: Ido Schimmel Signed-off-by: Marco Elver --- include/linux/skbuff.h | 37 +++++++++++++------------------------ lib/Kconfig.debug | 1 - net/core/skbuff.c | 12 +----------- 3 files changed, 14 insertions(+), 36 deletions(-) base-commit: 470dfd808ac4135f313967f9d3e107b87fc6a0b3 diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 0a1239819fd2..333bcdc39635 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -701,6 +701,7 @@ typedef unsigned char *sk_buff_data_t; * @transport_header: Transport layer header * @network_header: Network layer header * @mac_header: Link layer header + * @kcov_handle: KCOV remote handle for remote coverage collection * @tail: Tail pointer * @end: End pointer * @head: Head of buffer @@ -904,6 +905,10 @@ struct sk_buff { __u16 network_header; __u16 mac_header; +#ifdef CONFIG_KCOV + u64 kcov_handle; +#endif + /* private: */ __u32 headers_end[0]; /* public: */ @@ -4150,9 +4155,6 @@ enum skb_ext_id { #endif #if IS_ENABLED(CONFIG_MPTCP) SKB_EXT_MPTCP, -#endif -#if IS_ENABLED(CONFIG_KCOV) - SKB_EXT_KCOV_HANDLE, #endif SKB_EXT_NUM, /* must be last */ }; @@ -4608,35 +4610,22 @@ static inline void skb_reset_redirect(struct sk_buff *skb) #endif } -#if IS_ENABLED(CONFIG_KCOV) && IS_ENABLED(CONFIG_SKB_EXTENSIONS) static inline void skb_set_kcov_handle(struct sk_buff *skb, const u64 kcov_handle) { - /* Do not allocate skb extensions only to set kcov_handle to zero - * (as it is zero by default). However, if the extensions are - * already allocated, update kcov_handle anyway since - * skb_set_kcov_handle can be called to zero a previously set - * value. - */ - if (skb_has_extensions(skb) || kcov_handle) { - u64 *kcov_handle_ptr = skb_ext_add(skb, SKB_EXT_KCOV_HANDLE); - - if (kcov_handle_ptr) - *kcov_handle_ptr = kcov_handle; - } +#ifdef CONFIG_KCOV + skb->kcov_handle = kcov_handle; +#endif } static inline u64 skb_get_kcov_handle(struct sk_buff *skb) { - u64 *kcov_handle = skb_ext_find(skb, SKB_EXT_KCOV_HANDLE); - - return kcov_handle ? *kcov_handle : 0; -} +#ifdef CONFIG_KCOV + return skb->kcov_handle; #else -static inline void skb_set_kcov_handle(struct sk_buff *skb, - const u64 kcov_handle) { } -static inline u64 skb_get_kcov_handle(struct sk_buff *skb) { return 0; } -#endif /* CONFIG_KCOV && CONFIG_SKB_EXTENSIONS */ + return 0; +#endif +} #endif /* __KERNEL__ */ #endif /* _LINUX_SKBUFF_H */ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 826a205ffd1c..1d15cdaf1b89 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1879,7 +1879,6 @@ config KCOV depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS select DEBUG_FS select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC - select SKB_EXTENSIONS if NET help KCOV exposes kernel code coverage information in a form suitable for coverage-guided fuzzing (randomized testing). diff --git a/net/core/skbuff.c b/net/core/skbuff.c index ffe3dcc0ebea..070b1077d976 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -233,6 +233,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, skb->end = skb->tail + size; skb->mac_header = (typeof(skb->mac_header))~0U; skb->transport_header = (typeof(skb->transport_header))~0U; + skb_set_kcov_handle(skb, kcov_common_handle()); /* make sure we initialize shinfo sequentially */ shinfo = skb_shinfo(skb); @@ -249,9 +250,6 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, fclones->skb2.fclone = SKB_FCLONE_CLONE; } - - skb_set_kcov_handle(skb, kcov_common_handle()); - out: return skb; nodata: @@ -285,8 +283,6 @@ static struct sk_buff *__build_skb_around(struct sk_buff *skb, memset(shinfo, 0, offsetof(struct skb_shared_info, dataref)); atomic_set(&shinfo->dataref, 1); - skb_set_kcov_handle(skb, kcov_common_handle()); - return skb; } @@ -4208,9 +4204,6 @@ static const u8 skb_ext_type_len[] = { #if IS_ENABLED(CONFIG_MPTCP) [SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext), #endif -#if IS_ENABLED(CONFIG_KCOV) - [SKB_EXT_KCOV_HANDLE] = SKB_EXT_CHUNKSIZEOF(u64), -#endif }; static __always_inline unsigned int skb_ext_total_length(void) @@ -4227,9 +4220,6 @@ static __always_inline unsigned int skb_ext_total_length(void) #endif #if IS_ENABLED(CONFIG_MPTCP) skb_ext_type_len[SKB_EXT_MPTCP] + -#endif -#if IS_ENABLED(CONFIG_KCOV) - skb_ext_type_len[SKB_EXT_KCOV_HANDLE] + #endif 0; }