From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BCC8C6FA82 for ; Fri, 16 Sep 2022 17:29:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229494AbiIPR3Q (ORCPT ); Fri, 16 Sep 2022 13:29:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229454AbiIPR3P (ORCPT ); Fri, 16 Sep 2022 13:29:15 -0400 Received: from mail-lf1-x12e.google.com (mail-lf1-x12e.google.com [IPv6:2a00:1450:4864:20::12e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC05EB5A72; Fri, 16 Sep 2022 10:29:14 -0700 (PDT) Received: by mail-lf1-x12e.google.com with SMTP id k10so36634000lfm.4; Fri, 16 Sep 2022 10:29:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date; bh=c99THgg/Qu0Uq0g1n2HvJ4GdbvThpErIDXzsQyV5Y5M=; b=eN2BMBgsZzIHstlT6w6/JlqB6fmfOVwchpgbw5yUUQ1CVP9LpL7cwDinWmTalaZh1K B8eGSg8d56nehxCAwsIvboZ+spzR5QjQQoc0Tob9ul1uSUQKIA3x5erYAdxwgdbYI1Xb Y1OOhV66eIT7XWPjDXjkqhEIpqHro8TQ0Bhpj/lVv1BZ0852s2vlDJBEjPehSU9MrGfE 07Yu65TPUquxzWtLydmFCxnYulixscsCAK73Z7RMfcOIR6jWb4KWCw3SzipQP4NN9SYY Dx8wEzM9p8S/u2ZWqdc+fmGTjt5CjJaxcvRmPNMgG7KWaNSPcaBuGHvAkR/rYPpPFyJ9 aTGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date; bh=c99THgg/Qu0Uq0g1n2HvJ4GdbvThpErIDXzsQyV5Y5M=; b=eWXWS/ibbMhr+ka7dovCjUNyBT7LnbGGJvhD2C2ghieZ/BOE/LYfDw78BWzfcmKHP0 hDDj8ZwGW88Vh/97gd2yI7znFuwIfgNHC9SY/Qfy1a9X/nGHUGCvxZgB/wMJWAaN3D88 QJMDJtsoJwzoIwo2Q0nd5HIMXPPtmaS0hZT5D4Zwsx6F9RBZO+0ckxdJe9D7Nv47J0N8 KEnpLd0gJ21kPMEA2mOvAe7FfFT+WftGu7zLU027nR0mRuge49erssO5X0JiMlPwsd6d Ogv9if1Zufgs1rqFiODyBNiaCzy8zqjqIJmbOjEamdE87g8C8+NWyko53ycDCqvKc2zS YeMQ== X-Gm-Message-State: ACrzQf0ntCQFqRrMAhHgIWVqa6xcf8IBV6jl8LzJKrk5vcKWztTqJpTU WucPGVglY8RAt3CZVdiQXzg= X-Google-Smtp-Source: AMsMyM7G12shYaSwRYpiyRnjwgOShehtfYm9M38UQS6WG2ub/wqwZyBZ/jAB4NB382PL6nr4GKMEKA== X-Received: by 2002:a19:e044:0:b0:497:14fd:326f with SMTP id g4-20020a19e044000000b0049714fd326fmr1941972lfj.332.1663349353017; Fri, 16 Sep 2022 10:29:13 -0700 (PDT) Received: from pc636 (host-90-235-8-56.mobileonline.telia.com. [90.235.8.56]) by smtp.gmail.com with ESMTPSA id q14-20020a056512210e00b00492cfecf1c0sm3592686lfr.245.2022.09.16.10.29.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Sep 2022 10:29:12 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Fri, 16 Sep 2022 19:29:09 +0200 To: Kees Cook Cc: Matthew Wilcox , Uladzislau Rezki , Andrew Morton , Yu Zhao , dev@der-flo.net, linux-mm@kvack.org, linux-hardening@vger.kernel.org, Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, x86@kernel.org, linux-perf-users@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH 3/3] usercopy: Add find_vmap_area_try() to avoid deadlocks Message-ID: References: <20220916135953.1320601-1-keescook@chromium.org> <20220916135953.1320601-4-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220916135953.1320601-4-keescook@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On Fri, Sep 16, 2022 at 06:59:57AM -0700, Kees Cook wrote: > The check_object_size() checks under CONFIG_HARDENED_USERCOPY need to be > more defensive against running from interrupt context. Use a best-effort > check for VMAP areas when running in interrupt context > > Suggested-by: Matthew Wilcox > Link: https://lore.kernel.org/linux-mm/YyQ2CSdIJdvQPSPO@casper.infradead.org > Cc: Andrew Morton > Cc: Yu Zhao > Cc: dev@der-flo.net > Cc: linux-mm@kvack.org > Cc: linux-hardening@vger.kernel.org > Signed-off-by: Kees Cook > --- > include/linux/vmalloc.h | 1 + > mm/usercopy.c | 11 ++++++++++- > mm/vmalloc.c | 11 +++++++++++ > 3 files changed, 22 insertions(+), 1 deletion(-) > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > index 096d48aa3437..c8a00f181a11 100644 > --- a/include/linux/vmalloc.h > +++ b/include/linux/vmalloc.h > @@ -216,6 +216,7 @@ void free_vm_area(struct vm_struct *area); > extern struct vm_struct *remove_vm_area(const void *addr); > extern struct vm_struct *find_vm_area(const void *addr); > struct vmap_area *find_vmap_area(unsigned long addr); > +struct vmap_area *find_vmap_area_try(unsigned long addr); > > static inline bool is_vm_area_hugepages(const void *addr) > { > diff --git a/mm/usercopy.c b/mm/usercopy.c > index c1ee15a98633..4a371099ac64 100644 > --- a/mm/usercopy.c > +++ b/mm/usercopy.c > @@ -173,7 +173,16 @@ static inline void check_heap_object(const void *ptr, unsigned long n, > } > > if (is_vmalloc_addr(ptr)) { > - struct vmap_area *area = find_vmap_area(addr); > + struct vmap_area *area; > + > + if (unlikely(in_interrupt())) { > + area = find_vmap_area_try(addr); > + /* Give up under interrupt to avoid deadlocks. */ > + if (!area) > + return; > + } else { > + area = find_vmap_area(addr); > + } > > if (!area) > usercopy_abort("vmalloc", "no area", to_user, 0, n); > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index dd6cdb201195..f14f1902c2f6 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -1840,6 +1840,17 @@ struct vmap_area *find_vmap_area(unsigned long addr) > return va; > } > > +struct vmap_area *find_vmap_area_try(unsigned long addr) > I think it makes sense to add a comment of having such function and for which context it is supposed to be used. Maybe rename it to something with "atomic" prefix. Thanks. -- Uladzislau Rezki