From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9B1A06EB53 for ; Thu, 14 Mar 2024 11:09:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710414582; cv=none; b=XCwPQ4oN3T20r9Iy1InttplWBdl2oYFwY8E+o/j1wnH+KCUn1TU0tO39K4JF8gZAPK7Cy5jr64/8wEgBUmasC6xLR97DRdpXA/fEvdNHMl+bcBWCdm5pP8ThujJaBOTevDfXuvBhdzLGAtjRrjChWMMyiPi8ywE6mJHhuXT+EmQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710414582; c=relaxed/simple; bh=RaseM/+KoqOPYNmXu1HCiER1tZgWMTC85atLNfK0kqM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XqyXPPT8wi04ZOw6HvNsywXx1lG52CRbFJzShLNClkEtljlTbCz8dZUt2Q2B6vY8qUUkMVMBRLKBIE5db28d8PPGVA69YouvhqIB07PkrmB2/aSWTefPgYQihNMtg9aSOHxzoQhLCbzTMQaMLz5uUH9QwntM+BFQ8h1xUrEZFeY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=moDtbAil; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="moDtbAil" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDC2CC433F1; Thu, 14 Mar 2024 11:09:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1710414582; bh=RaseM/+KoqOPYNmXu1HCiER1tZgWMTC85atLNfK0kqM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=moDtbAilM7o1ksXGdCj1d5zYc0JpDsUwsaE3PufyJkNl2X5/SgtMCqKEXbKB/Phe6 aCFmozE9ar2kMxt5+mISFKncM7Lzc0b2sEYSqhGTpwsCZCy3hLekEDRVX6JJzYc7po ep2BqVh3RP2zfslNmYho2TQovdJh1otUqD3v9mn9LX0keJ7QXBD6RLTAl8nqkqan9p 9jlwjOLk8FhbjKoxjvTB7NbngEJ7oKP47z+rRNPoIvP9DSmScveT77eYHbPNYnqMri s2bqCTkZEK30jDZh/l/zDXwnMJnCSEiX2jlCYkrVTZ+1wR4bSLRegx0gX/3dhe6M5w F5DVA15MCCdbA== Date: Thu, 14 Mar 2024 11:09:38 +0000 From: Lee Jones To: Michal Hocko Cc: cve@kernel.org, linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Felix Kuehling Subject: Re: CVE-2024-26628: drm/amdkfd: Fix lock dependency warning Message-ID: <20240314110938.GM1522089@google.com> References: <2024030649-CVE-2024-26628-f6ce@gregkh> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, 08 Mar 2024, Michal Hocko wrote: > On Wed 06-03-24 06:46:11, Greg KH wrote: > [...] > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(&svms->lock); > > lock(&mm->mmap_lock); > > lock(&svms->lock); > > lock((work_completion)(&svm_bo->eviction_work)); > > > > I believe this cannot really lead to a deadlock in practice, because > > svm_range_evict_svm_bo_worker only takes the mmap_read_lock if the BO > > refcount is non-0. That means it's impossible that svm_range_bo_release > > is running concurrently. However, there is no good way to annotate this. > > OK, so is this even a bug (not to mention a security/weakness)? Looks like the patch fixes a warning which can crash some kernels. So the CVE appears to be fixing that, rather than the impossible deadlock. -- Lee Jones [李琼斯]