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[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> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663349354; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=c99THgg/Qu0Uq0g1n2HvJ4GdbvThpErIDXzsQyV5Y5M=; b=Uu0g3IgUosnRHKvE4qGi73zVbw+iuf6k3K5nNjqF6rwYV6rXXakcuUli8JqkgazezI67Ej /vCjvSY2MFR8srk49PVrin62FMsKbIyBLi3qYCqAiGQoGZhkCJ2yMNtnzlgEO2QV8telWL jyCVYwpvlmYhKx376Ec8pw+auw3RHMk= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=eN2BMBgs; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf12.hostedemail.com: domain of urezki@gmail.com designates 209.85.167.52 as permitted sender) smtp.mailfrom=urezki@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663349354; a=rsa-sha256; cv=none; b=IC/YAvn+vNyQZ2AnHBpyfBqhrcO1MSePT7RB4SyfvUiRsXmnegJDhksB7IC2W8y/N94Q1a LPCDhnRA+7nUri0vo1k0wprVoEGBa54y/YPq9ZcNZNLyr6ZMQNWnvo7h0THgtColoF06cd hSY+TdmvQND6Y8dBsyEd1BlrkeUahSs= X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D3E7E400C8 X-Rspam-User: X-Stat-Signature: 5ka41xbnsxiynr5syneixomubphke97d Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=eN2BMBgs; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf12.hostedemail.com: domain of urezki@gmail.com designates 209.85.167.52 as permitted sender) smtp.mailfrom=urezki@gmail.com X-HE-Tag: 1663349354-828833 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: 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