From patchwork Fri Dec 4 02:43:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miles Chen X-Patchwork-Id: 11950439 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=-23.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_GIT 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 5F41FC4361B for ; Fri, 4 Dec 2020 02:44:11 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 061D7224B8 for ; Fri, 4 Dec 2020 02:44:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 061D7224B8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:To:From: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=4ZSnT1UWqdfgWa7AmNUIHBZ6qATKxifsMM4y0UZttRM=; b=VlU/f69USx8xzRd3rP4XwHpnYH HuDDxvfaQA9ZXZvLpvn/aUICpSgums5G6mcjzI4cIJ2DnmIIv3nlKsVJ8Jjrtuw39ssqKntTU3xB0 2IlsqdpdYtVFzO4jwNGe6D+7IaBP6Y0x9TbPDDDVw2daGluoDvZX7MZU6W5qZWqPg63ID5ZrVeBIW 9+26EY3cUYTV1qY4LIuzp2lSoMZo3bU1l3IAiIgJgUTnGkwF5Tu5snA2SyXguxR3OnrNctTJNsBRK GiYUl0wtreaEZBANniUok8fNa4DbhAXsYVveQHXMLTt9AUr5ZGeXy1kT6S/n9Shogf7+1j8KUWP9r LuMXgUxw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kl14j-0000Lw-BG; Fri, 04 Dec 2020 02:44:01 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kl14c-0000JF-K6 for linux-mediatek@lists.infradead.org; Fri, 04 Dec 2020 02:43:56 +0000 X-UUID: 6024173dec3c422db3065ca4d5098797-20201203 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=BOF1RXQyljLarFtu3NpN19aJNXFNaN+WUDmXzMB996E=; b=uNvjmpPgL/uo9jquVCG/hdcDEzRjHYHR1ZZo7KszpfQV0I1FmG3FWVRiHkb1ZbLm7dbyWJEe5hlS+WX7CZSdtJ3aeMnkQik9MN7XaFiUrXLXrc6zn4FxYWUUg0leNfgXr32O8nJc4J8tlc6e61AGPgKq+b40HHfOSir4e9VFLqw=; X-UUID: 6024173dec3c422db3065ca4d5098797-20201203 Received: from mtkcas67.mediatek.inc [(172.29.193.45)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 688052889; Thu, 03 Dec 2020 18:43:50 -0800 Received: from mtkmbs08n1.mediatek.inc (172.21.101.55) by MTKMBS62DR.mediatek.inc (172.29.94.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 3 Dec 2020 18:43:49 -0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs08n1.mediatek.inc (172.21.101.55) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 4 Dec 2020 10:43:48 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Fri, 4 Dec 2020 10:43:50 +0800 From: Miles Chen To: Alexey Dobriyan , Andrew Morton Subject: [PATCH v3] proc: use untagged_addr() for pagemap_read addresses Date: Fri, 4 Dec 2020 10:43:47 +0800 Message-ID: <20201204024347.8295-1-miles.chen@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201203_214354_861770_F884E18D X-CRM114-Status: GOOD ( 21.09 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Song Bao Hua , Marco Elver , Catalin Marinas , wsd_upstream@mediatek.com, Andrey Konovalov , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Miles Chen , linux-mediatek@lists.infradead.org, "Eric W . Biederman" , Andrey Ryabinin , linux-fsdevel@vger.kernel.org, Alexander Potapenko , Vincenzo Frascino , Will Deacon , Dmitry Vyukov Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org When we try to visit the pagemap of a tagged userspace pointer, we find that the start_vaddr is not correct because of the tag. To fix it, we should untag the userspace pointers in pagemap_read(). I tested with 5.10-rc4 and the issue remains. Explanation from Catalin in [1]: :Arguably, that's a user-space bug since tagged file offsets were never :supported. In this case it's not even a tag at bit 56 as per the arm64 :tagged address ABI but rather down to bit 47. You could say that the :problem is caused by the C library (malloc()) or whoever created the :tagged vaddr and passed it to this function. It's not a kernel :regression as we've never supported it. : :Now, pagemap is a special case where the offset is usually not generated :as a classic file offset but rather derived by shifting a user virtual :address. I guess we can make a concession for pagemap (only) and allow :such offset with the tag at bit (56 - PAGE_SHIFT + 3). My test code is based on [2]: A userspace pointer which has been tagged by 0xb4: 0xb400007662f541c8 === userspace program === uint64 OsLayer::VirtualToPhysical(void *vaddr) { uint64 frame, paddr, pfnmask, pagemask; int pagesize = sysconf(_SC_PAGESIZE); off64_t off = ((uintptr_t)vaddr) / pagesize * 8; // off = 0xb400007662f541c8 / pagesize * 8 = 0x5a00003b317aa0 int fd = open(kPagemapPath, O_RDONLY); ... if (lseek64(fd, off, SEEK_SET) != off || read(fd, &frame, 8) != 8) { int err = errno; string errtxt = ErrorString(err); if (fd >= 0) close(fd); return 0; } ... } === kernel fs/proc/task_mmu.c === static ssize_t pagemap_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { ... src = *ppos; svpfn = src / PM_ENTRY_BYTES; // svpfn == 0xb400007662f54 start_vaddr = svpfn << PAGE_SHIFT; // start_vaddr == 0xb400007662f54000 end_vaddr = mm->task_size; /* watch out for wraparound */ // svpfn == 0xb400007662f54 // (mm->task_size >> PAGE) == 0x8000000 if (svpfn > mm->task_size >> PAGE_SHIFT) // the condition is true because of the tag 0xb4 start_vaddr = end_vaddr; ret = 0; while (count && (start_vaddr < end_vaddr)) { // we cannot visit correct entry because start_vaddr is set to end_vaddr int len; unsigned long end; ... } ... } [1] https://lore.kernel.org/patchwork/patch/1343258/ [2] https://github.com/stressapptest/stressapptest/blob/master/src/os.cc#L158 Cc: Andrew Morton Cc: Alexey Dobriyan Cc: Andrey Konovalov Cc: Alexander Potapenko Cc: Vincenzo Frascino Cc: Andrey Ryabinin Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Marco Elver Cc: Will Deacon Cc: Eric W. Biederman Cc: Song Bao Hua (Barry Song) Cc: stable@vger.kernel.org # v5.4- Signed-off-by: Miles Chen Reviewed-by: Vincenzo Frascino Reviewed-by: Catalin Marinas --- Change since v1: 1. Follow Eirc's and Catalin's suggestion to avoid overflow 2. Cc to stable v5.4- 3. add explaination from Catalin to the commit message Change since v2: 1. replace less-than with less-than or equal 2. Fix bad spelling in commit message 3. Fix will's email address --- fs/proc/task_mmu.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 217aa2705d5d..ee5a235b3056 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1599,11 +1599,15 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, src = *ppos; svpfn = src / PM_ENTRY_BYTES; - start_vaddr = svpfn << PAGE_SHIFT; end_vaddr = mm->task_size; /* watch out for wraparound */ - if (svpfn > mm->task_size >> PAGE_SHIFT) + start_vaddr = end_vaddr; + if (svpfn <= (ULONG_MAX >> PAGE_SHIFT)) + start_vaddr = untagged_addr(svpfn << PAGE_SHIFT); + + /* Ensure the address is inside the task */ + if (start_vaddr > mm->task_size) start_vaddr = end_vaddr; /*