From patchwork Tue Jul 30 01:57:29 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miles Chen X-Patchwork-Id: 11064819 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C22D9112C for ; Tue, 30 Jul 2019 01:57:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AE8ED286D0 for ; Tue, 30 Jul 2019 01:57:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A0ADB286DA; Tue, 30 Jul 2019 01:57:38 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 85013286D0 for ; Tue, 30 Jul 2019 01:57:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CB9EA8E0003; Mon, 29 Jul 2019 21:57:34 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id C910A8E0002; Mon, 29 Jul 2019 21:57:34 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B7F678E0003; Mon, 29 Jul 2019 21:57:34 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by kanga.kvack.org (Postfix) with ESMTP id 8307E8E0002 for ; Mon, 29 Jul 2019 21:57:34 -0400 (EDT) Received: by mail-pg1-f200.google.com with SMTP id b18so39491561pgg.8 for ; Mon, 29 Jul 2019 18:57:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:from:to:cc :subject:date:message-id:mime-version; bh=4nSt4+4z0yU8Ud2djyr/hMGCEWv/LT687HI00JxUk3k=; b=gPnypNzk8gDL4GcsBsz+PnD86rdEiQeXrrACGj71Jyaum1daaPJCvJi2hj7ZB0tBav E4jNJgdxKd+tAdER8PcckYNthMRmqSkNiPa3HArk5hKXIgsm4BQQzkXEwfEDY/la97o1 Hx5uWJ/+fpnM+Bk3seeBYxQlwZ+NgpZ4apOpvbdk6Djt1klCd9iP8yV9dZdB+1H8mnoN /Sxd9k9Ff2hGUIwlrGhkrApzEjr6hKcbhLPTNrQ0/car1VeEy14AWnM0cm+deozNCe6O EfXLjqGsm28gl1qPKFsM3VRFX1WMtareiRYZLM27EjDmF+rv8tyxgUwtZQmRT+MZFHfx Vd9g== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of miles.chen@mediatek.com designates 210.61.82.184 as permitted sender) smtp.mailfrom=miles.chen@mediatek.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=mediatek.com X-Gm-Message-State: APjAAAW8EP2v/3/o5t9x9IVqr4hVtK7SFwyq51kf7LK3/GoQPUJjgm/r 05dzw1koSgaYojfGt7/87iboXgPSPwK3xSoM4UleuR5KYA9gk4ybEnQcK0TZyRNJc2kk7/b4Lrp BWrrjhPX0NQNbHRR4dvdXeW/nJr3YvWHE+fh/iNeKcLtcJrg21Z9fXjnn2nq06/q40g== X-Received: by 2002:a17:90a:8a84:: with SMTP id x4mr112941042pjn.105.1564451854179; Mon, 29 Jul 2019 18:57:34 -0700 (PDT) X-Google-Smtp-Source: APXvYqzUWlh4ZpKhYl2CxSyeR8pvbO3jJYKhgmVVQ8d6vlp0gkeej7vPC277xFK6cHRtx/eemu3G X-Received: by 2002:a17:90a:8a84:: with SMTP id x4mr112941001pjn.105.1564451853136; Mon, 29 Jul 2019 18:57:33 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1564451853; cv=none; d=google.com; s=arc-20160816; b=QqRsTmJDM4ZuI86h7tSGfh1jYmcOVDVEY9axGYOibU5gaGbewDnndgwybigAvKz2QV gsPnVdkpO9H/8V6jubic6R7aeXEeHWIAMR8RIL2yIzj6nhbPhYgWf90yIChyRHA5xoOD WE2ZRsGL2RFbgcJzGZ4FJfKN8vzCxjOFVp7dJpt5EEDy92oOsNZ7D04gU1DMeBJO01be wWAXD8TPUTlPFMPCghnuVx48hrM7ZTAo+Vf61b0/bLC724gGra7PRG1nDEsEOqR+3RSH w7+tO06cdlll8nXlI/zvFvxbXJ5cQ0zYVy66qDhmSosRH6yPt8nXZvQtHTgnhb2Swapv qkww== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:message-id:date:subject:cc:to:from; bh=4nSt4+4z0yU8Ud2djyr/hMGCEWv/LT687HI00JxUk3k=; b=YA7XXL12X6UOhqBVCN06uXaHtnARAYWRHfvYzM7FDjrb/474ePbIHOx4nWmt6f0nWV aXoJE6ybbTehZVknp1uIklF5DWZ4bChZDOvQfYdvkTNgFAVb2pnQgNOKYvuhjwXJrLNy hZjvFy/Mrd5+tBTR8vBw9eWPjzh2GSybIBns3UtpdRVb+y6XB9AKz0TYROAHuZYb4FdL s2+KfsjIM1UPkLve6YYyw7FRJcNCAUFZ+UXHWGI875dqjg3eB90G8Ioqja0i9FbpKu3J DBfbeg+31vwtPH5bR8dfkovqw5OrV5dysTH9x3N3lBwcxNB2knnkEBCliJHZKR7I12WF GPUg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of miles.chen@mediatek.com designates 210.61.82.184 as permitted sender) smtp.mailfrom=miles.chen@mediatek.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=mediatek.com Received: from mailgw02.mediatek.com ([210.61.82.184]) by mx.google.com with ESMTP id g191si28538863pgc.331.2019.07.29.18.57.32 for ; Mon, 29 Jul 2019 18:57:33 -0700 (PDT) Received-SPF: pass (google.com: domain of miles.chen@mediatek.com designates 210.61.82.184 as permitted sender) client-ip=210.61.82.184; Authentication-Results: mx.google.com; spf=pass (google.com: domain of miles.chen@mediatek.com designates 210.61.82.184 as permitted sender) smtp.mailfrom=miles.chen@mediatek.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=mediatek.com X-UUID: b2d537855ff247a59ab2e8562b6d0a84-20190730 X-UUID: b2d537855ff247a59ab2e8562b6d0a84-20190730 Received: from mtkcas08.mediatek.inc [(172.21.101.126)] by mailgw02.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.10 Build 0707 with TLS) with ESMTP id 1386982138; Tue, 30 Jul 2019 09:57:30 +0800 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs07n2.mediatek.inc (172.21.101.141) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Tue, 30 Jul 2019 09:57:30 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Tue, 30 Jul 2019 09:57:30 +0800 From: Miles Chen To: Johannes Weiner , Michal Hocko , Vladimir Davydov CC: , , , , , Miles Chen Subject: [PATCH v4] mm: memcontrol: fix use after free in mem_cgroup_iter() Date: Tue, 30 Jul 2019 09:57:29 +0800 Message-ID: <20190730015729.4406-1-miles.chen@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP This patch is sent to report an use after free in mem_cgroup_iter() after merging commit: be2657752e9e "mm: memcg: fix use after free in mem_cgroup_iter()". I work with android kernel tree (4.9 & 4.14), and the commit: be2657752e9e "mm: memcg: fix use after free in mem_cgroup_iter()" has been merged to the trees. However, I can still observe use after free issues addressed in the commit be2657752e9e. (on low-end devices, a few times this month) backtrace: css_tryget <- crash here mem_cgroup_iter shrink_node shrink_zones do_try_to_free_pages try_to_free_pages __perform_reclaim __alloc_pages_direct_reclaim __alloc_pages_slowpath __alloc_pages_nodemask To debug, I poisoned mem_cgroup before freeing it: static void __mem_cgroup_free(struct mem_cgroup *memcg) for_each_node(node) free_mem_cgroup_per_node_info(memcg, node); free_percpu(memcg->stat); + /* poison memcg before freeing it */ + memset(memcg, 0x78, sizeof(struct mem_cgroup)); kfree(memcg); } The coredump shows the position=0xdbbc2a00 is freed. (gdb) p/x ((struct mem_cgroup_per_node *)0xe5009e00)->iter[8] $13 = {position = 0xdbbc2a00, generation = 0x2efd} 0xdbbc2a00: 0xdbbc2e00 0x00000000 0xdbbc2800 0x00000100 0xdbbc2a10: 0x00000200 0x78787878 0x00026218 0x00000000 0xdbbc2a20: 0xdcad6000 0x00000001 0x78787800 0x00000000 0xdbbc2a30: 0x78780000 0x00000000 0x0068fb84 0x78787878 0xdbbc2a40: 0x78787878 0x78787878 0x78787878 0xe3fa5cc0 0xdbbc2a50: 0x78787878 0x78787878 0x00000000 0x00000000 0xdbbc2a60: 0x00000000 0x00000000 0x00000000 0x00000000 0xdbbc2a70: 0x00000000 0x00000000 0x00000000 0x00000000 0xdbbc2a80: 0x00000000 0x00000000 0x00000000 0x00000000 0xdbbc2a90: 0x00000001 0x00000000 0x00000000 0x00100000 0xdbbc2aa0: 0x00000001 0xdbbc2ac8 0x00000000 0x00000000 0xdbbc2ab0: 0x00000000 0x00000000 0x00000000 0x00000000 0xdbbc2ac0: 0x00000000 0x00000000 0xe5b02618 0x00001000 0xdbbc2ad0: 0x00000000 0x78787878 0x78787878 0x78787878 0xdbbc2ae0: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2af0: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2b00: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2b10: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2b20: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2b30: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2b40: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2b50: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2b60: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2b70: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2b80: 0x78787878 0x78787878 0x00000000 0x78787878 0xdbbc2b90: 0x78787878 0x78787878 0x78787878 0x78787878 0xdbbc2ba0: 0x78787878 0x78787878 0x78787878 0x78787878 In the reclaim path, try_to_free_pages() does not setup sc.target_mem_cgroup and sc is passed to do_try_to_free_pages(), ..., shrink_node(). In mem_cgroup_iter(), root is set to root_mem_cgroup because sc->target_mem_cgroup is NULL. It is possible to assign a memcg to root_mem_cgroup.nodeinfo.iter in mem_cgroup_iter(). try_to_free_pages struct scan_control sc = {...}, target_mem_cgroup is 0x0; do_try_to_free_pages shrink_zones shrink_node mem_cgroup *root = sc->target_mem_cgroup; memcg = mem_cgroup_iter(root, NULL, &reclaim); mem_cgroup_iter() if (!root) root = root_mem_cgroup; ... css = css_next_descendant_pre(css, &root->css); memcg = mem_cgroup_from_css(css); cmpxchg(&iter->position, pos, memcg); My device uses memcg non-hierarchical mode. When we release a memcg: invalidate_reclaim_iterators() reaches only dead_memcg and its parents. If non-hierarchical mode is used, invalidate_reclaim_iterators() never reaches root_mem_cgroup. static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg) { struct mem_cgroup *memcg = dead_memcg; for (; memcg; memcg = parent_mem_cgroup(memcg) ... } So the use after free scenario looks like: CPU1 CPU2 try_to_free_pages do_try_to_free_pages shrink_zones shrink_node mem_cgroup_iter() if (!root) root = root_mem_cgroup; ... css = css_next_descendant_pre(css, &root->css); memcg = mem_cgroup_from_css(css); cmpxchg(&iter->position, pos, memcg); invalidate_reclaim_iterators(memcg); ... __mem_cgroup_free() kfree(memcg); try_to_free_pages do_try_to_free_pages shrink_zones shrink_node mem_cgroup_iter() if (!root) root = root_mem_cgroup; ... mz = mem_cgroup_nodeinfo(root, reclaim->pgdat->node_id); iter = &mz->iter[reclaim->priority]; pos = READ_ONCE(iter->position); css_tryget(&pos->css) <- use after free To avoid this, we should also invalidate root_mem_cgroup.nodeinfo.iter in invalidate_reclaim_iterators(). Change since v1: Add a comment to explain why we need to handle root_mem_cgroup separately. Rename invalid_root to invalidate_root. Change since v2: Add fix tag Change since v3: Remove confusing 'invalidate_root', make the code easier to read Fixes: 5ac8fb31ad2e ("mm: memcontrol: convert reclaim iterator to simple css refcounting") Cc: Johannes Weiner Cc: Michal Hocko Signed-off-by: Miles Chen Acked-by: Michal Hocko --- mm/memcontrol.c | 39 +++++++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 10 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index cdbb7a84cb6e..8a2a2d5cfc26 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1130,26 +1130,45 @@ void mem_cgroup_iter_break(struct mem_cgroup *root, css_put(&prev->css); } -static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg) +static void __invalidate_reclaim_iterators(struct mem_cgroup *from, + struct mem_cgroup *dead_memcg) { - struct mem_cgroup *memcg = dead_memcg; struct mem_cgroup_reclaim_iter *iter; struct mem_cgroup_per_node *mz; int nid; int i; - for (; memcg; memcg = parent_mem_cgroup(memcg)) { - for_each_node(nid) { - mz = mem_cgroup_nodeinfo(memcg, nid); - for (i = 0; i <= DEF_PRIORITY; i++) { - iter = &mz->iter[i]; - cmpxchg(&iter->position, - dead_memcg, NULL); - } + for_each_node(nid) { + mz = mem_cgroup_nodeinfo(from, nid); + for (i = 0; i <= DEF_PRIORITY; i++) { + iter = &mz->iter[i]; + cmpxchg(&iter->position, + dead_memcg, NULL); } } } +static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg) +{ + struct mem_cgroup *memcg = dead_memcg; + struct mem_cgroup *last; + + do { + __invalidate_reclaim_iterators(memcg, dead_memcg); + last = memcg; + } while (memcg = parent_mem_cgroup(memcg)); + + /* + * When cgruop1 non-hierarchy mode is used, + * parent_mem_cgroup() does not walk all the way up to the + * cgroup root (root_mem_cgroup). So we have to handle + * dead_memcg from cgroup root separately. + */ + if (last != root_mem_cgroup) + __invalidate_reclaim_iterators(root_mem_cgroup, + dead_memcg); +} + /** * mem_cgroup_scan_tasks - iterate over tasks of a memory cgroup hierarchy * @memcg: hierarchy root