From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 897361B9B35 for ; Thu, 29 Aug 2024 19:14:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724958863; cv=none; b=tbiypij2WHYjhiP3qVvXU/BMHz1QQ4aYuxy+yPGmEUlhQ3qweCAsAEtcF8ghuxiT5WIiQ9lA171astgkC529E/LIaE4UucungrUy8IgxFMjRGisQ/td5IWwf6bD7NlpW1DzelPj41HmqRoNkfU4xVWmQpqgJP1rXw+TIgprnICc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724958863; c=relaxed/simple; bh=DLYVbOyAOXiOoZ7O1FIx1sY+tLPrpj43JW66pjzCKCY=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=d+mGrDdLpzwmwcX0o7DpKgf+bZoqoOuVm5KajyHWUJu+h60PtyTyHRkphjjaPni1RhUfQMU9IBwebPkkmMNfUPUAo+BTvD6LrvlLOg2PtgTzyxpmqeRnFhdI7u0ixKH7aXon6Nz7RU8DbWQCcdqOSTPTakpO4aToClwfxrFIDfA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=2vA6tzHe; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="2vA6tzHe" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-203a142c31dso11318045ad.3 for ; Thu, 29 Aug 2024 12:14:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1724958862; x=1725563662; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=p/FgfdhlBFPaII3VwKu8OXKCzJuOVcc3OJ6Xh9EER4Y=; b=2vA6tzHedxqaioiTOTWkPLjs6KcByk4qEKdhPRWSBQeqRCMCNYjrr/925PRUh8EuYT K/48/mOXFxAG0n0O2dlrmTFtTYOalQpxNRC85wTTXGLHUoJqKsDni8MPNYx3qEKzsGuk zcC89VwsQklKXY3WPXTwsX5Bszf4fxkhbxsjMwA2fVePCmFx0O7bvekRB7Fx8d8d11+e euhw9Eai2JBw/RsxACIfOBmuzEBFml46Gmm9/+VP8vtmOBPn7AZmV8tUsgKYxGi/VQxa cJGnjMoVJRbTpHV3ad1KL0COvfGVEDvMQjHL6OWQj/kRzTstanuDT/DQ4/fycrRZzR47 tnmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724958862; x=1725563662; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=p/FgfdhlBFPaII3VwKu8OXKCzJuOVcc3OJ6Xh9EER4Y=; b=AHGwQ9RDLNa2VaOk/WU1V3BX/73CdYz+zrCfmzdlcpV8Ii1BTmU7XWrKAdkSZM7x8p BHt2iypsIBU2yGb6SRq8q7jAUsMw6+iJ2i3WTeQ/j2J6XjGsKzE9v6s4x3JgfOIXBTMT 3BRC3pisS/rx56HQVUN1IUkZR/ma9mSFrBFw0iOL7sWz/Jms+cSDS6rQ2lWTaslVTtyo LLB0CmaznPKJsl2ONcAfjvDMCWzF263L5iun6xftgUCEWoS5BasDOI/CEwu7DgkBlZkI iZMInQE5v+WRQmCaQ9fxE8mve/HoLvpOD0mr4z1d/Ie7zzqGYLLwmE6wersbGDzd/xxw s+AA== X-Forwarded-Encrypted: i=1; AJvYcCVWn76gpQjTgKE2z9kbC3mHmfaM0aNlZu/w+ADCwKIzEN91yVsx/Fq1q685gQkotH1lAygGm3utxZAz5ng=@vger.kernel.org X-Gm-Message-State: AOJu0YzujMrx7wQkFpmw5xG2wawPqG7hOP/5EigHpXbuhiiIeugzFvWd 73tlgmeDreZkcZuDWqgZdxXgovuSwXC/1LozEXB/y/umxwZ56D7g1j+/duzESnRxKSQzmtMLnGf JbQ== X-Google-Smtp-Source: AGHT+IH5ChutmsP6103JjAhCqMw5SQ3KVVJLqVu9D4hnLR2shZ7oURw/Tuxrcs9dgf/1fd1kguor7MJA+VU= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:902:d508:b0:1fc:5ef0:23d1 with SMTP id d9443c01a7336-2050c3dbfc1mr1999975ad.7.1724958861863; Thu, 29 Aug 2024 12:14:21 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 29 Aug 2024 12:14:13 -0700 In-Reply-To: <20240829191413.900740-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240829191413.900740-1-seanjc@google.com> X-Mailer: git-send-email 2.46.0.469.g59c65b2a67-goog Message-ID: <20240829191413.900740-3-seanjc@google.com> Subject: [PATCH 2/2] KVM: Harden guest memory APIs against out-of-bounds accesses From: Sean Christopherson To: Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, zyr_ms@outlook.com, Sean Christopherson Content-Type: text/plain; charset="UTF-8" When reading or writing a guest page, WARN and bail if offset+len would result in a read to a different page so that KVM bugs are more likely to be detected, and so that any such bugs are less likely to escalate to an out-of-bounds access. E.g. if userspace isn't using guard pages and the target page is at the end of a memslot. Note, KVM already hardens itself in similar APIs, e.g. in the "cached" variants, it's just the vanilla APIs that are playing with fire. Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e036c17c4342..909d9dd7b448 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3276,6 +3276,9 @@ static int __kvm_read_guest_page(struct kvm_memory_slot *slot, gfn_t gfn, int r; unsigned long addr; + if (WARN_ON_ONCE(offset + len > PAGE_SIZE)) + return -EFAULT; + addr = gfn_to_hva_memslot_prot(slot, gfn, NULL); if (kvm_is_error_hva(addr)) return -EFAULT; @@ -3349,6 +3352,9 @@ static int __kvm_read_guest_atomic(struct kvm_memory_slot *slot, gfn_t gfn, int r; unsigned long addr; + if (WARN_ON_ONCE(offset + len > PAGE_SIZE)) + return -EFAULT; + addr = gfn_to_hva_memslot_prot(slot, gfn, NULL); if (kvm_is_error_hva(addr)) return -EFAULT; @@ -3379,6 +3385,9 @@ static int __kvm_write_guest_page(struct kvm *kvm, int r; unsigned long addr; + if (WARN_ON_ONCE(offset + len > PAGE_SIZE)) + return -EFAULT; + addr = gfn_to_hva_memslot(memslot, gfn); if (kvm_is_error_hva(addr)) return -EFAULT; -- 2.46.0.469.g59c65b2a67-goog