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 CB72A3C7E07 for ; Fri, 27 Mar 2026 07:28:17 +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=1774596497; cv=none; b=He19LOugvdHPMzH/3ZNVAmf5CP9sZfcQ1CRKfNUV01PxyH0VeOzjvRaOOY/OtiAkmK2rQPU91OLDH2BC/gSo4h5XnKn+isRpImkInhEM8pbI9xxNZNbDnT2p4e8GrZ4XCc2xlj0WCm0UUKR91OljQDa8m2//I0cKfuxWnrwK+Mo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774596497; c=relaxed/simple; bh=oZjRLfQFyXuW7OA2LGzqvvq2WkiEftnL6M6KOJhFXi0=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=q4kKwaOGEXvhJ7mbkmyVzNp/JWrmSu8tS5xoK3Sqc99JWaswRxpSyv+VrXdWXiFynAUrPqdVS2k9PqdTtgVJ9dLB/dsMzBKbm0v9jTtmK8tI28fbHLrZuwp0wr4kUP8LcjoAo6jwgIsBxaU2DfsXIDMdHBf9ELhcfx7Ur0c6OkI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZbQApM3T; 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="ZbQApM3T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AECAC19424; Fri, 27 Mar 2026 07:28:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774596497; bh=oZjRLfQFyXuW7OA2LGzqvvq2WkiEftnL6M6KOJhFXi0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ZbQApM3TnZPYGnJynNNn1PjWSm/VbBuqYwDSuSmVP3KYMXp5bs9vIyxnf8N3wAAPm 4hkmLKZMSYvjr09TST7eBcYVhR/Dvrrw3Q9pML8c1uL27uSX2M9SxckV7uhsjc4G/i DktqCyuh+jkuyRCW4yFna1Ms/rtgnQCtvKuEMNaHZlpnB7hSdw/OYaGoRJfP1NIkLL emFEry3AaChF6/3rNqh46Gs8bkkK7Bcc98PK36PpkkcCe7bhTS/4/zEdOgjAtXP/Ci Jixsy0K6eKkeQhzQfKAgVgY/mj4Bjnz96GHxtnMTVUWBRTHwyGP4SRDScajW7rtaLm RniRqHj8oSt6A== Date: Fri, 27 Mar 2026 16:28:12 +0900 From: Masami Hiramatsu (Google) To: David Laight Cc: Andrew Morton , Petr Mladek , Steven Rostedt , Andy Shevchenko , Rasmus Villemoes , Sergey Senozhatsky , linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 0/2] lib/vsprintf: Fixes size check Message-Id: <20260327162812.f657c7c01e1823fc874b2547@kernel.org> In-Reply-To: <20260326091212.5b370ff8@pumpkin> References: <177440550682.147866.1854734911195480940.stgit@devnote2> <20260324220458.3ca2bfeb393eedb5cc7ff52d@linux-foundation.org> <20260325102039.79afa79a@pumpkin> <20260326163944.1a7e83e7c1a70202c1a05deb@kernel.org> <20260326091212.5b370ff8@pumpkin> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 26 Mar 2026 09:12:12 +0000 David Laight wrote: > On Thu, 26 Mar 2026 16:39:44 +0900 > Masami Hiramatsu (Google) wrote: > > > On Wed, 25 Mar 2026 10:20:39 +0000 > > David Laight wrote: > > > > > On Tue, 24 Mar 2026 22:04:58 -0700 > > > Andrew Morton wrote: > > > > > > > On Wed, 25 Mar 2026 11:25:06 +0900 "Masami Hiramatsu (Google)" wrote: > > > > > > > > > Here is the 4th version of patches to fix vsnprintf(). > > > > > > > > > > - Fix to limit the size of width and precision. > > > > > - Warn if the return size is over INT_MAX. > > > > > > > > > > Previous version is here; > > > > > > > > > > https://lore.kernel.org/all/177410406326.38798.16853803119128725972.stgit@devnote2/ > > > > > > > > > > In this version, do clamp() the width and precision before checking it and > > > > > accept negative precision[1/3] and add Petr's Reviewed-by[2/2]. > > > > > > > > AI review has flagged a couple of possible issues: > > > > https://sashiko.dev/#/patchset/177440550682.147866.1854734911195480940.stgit@devnote2 > > > > > > I'd guess there are exactly 0 places where a negative precision is passed > > > to "%.*s" - if there were any someone would have complained about the > > > output being missing. > > > Checking all 759 cases grep -r '".*%.*\.%*s.*"' found will be tedious. > > > But pretty much all are 'namelen'. > > > > I also verified and found only one suspicious usage which can pass > > a negative precision. > > It is always called with a constant, in any case the string being output > is constant so nothing nasty can happen. Since this function is not a static function, it can be called anywhere in the module. So it is safer to check the indent is positive. > I didn't even see any recursive/loop calls that indent by significant amounts. > The code could use the more usual ("%*s", indent, ""), but it doesn't matter > much - mostly just a shorter line. I think the current code looks a bit tricky and not clear what it does. Maybe it is better to replace it with above usual usage. Thanks, > > David > > > > > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c > > index d2c7b1090df0..1f90775ea8a8 100644 > > --- a/drivers/gpu/drm/i915/i915_request.c > > +++ b/drivers/gpu/drm/i915/i915_request.c > > @@ -2224,7 +2224,7 @@ void i915_request_show(struct drm_printer *m, > > rcu_read_lock(); > > timeline = dma_fence_timeline_name((struct dma_fence *)&rq->fence); > > drm_printf(m, "%s%.*s%c %llx:%lld%s%s %s @ %dms: %s\n", > > - prefix, indent, " ", > > + prefix, max(0, indent), " ", > > queue_status(rq), > > rq->fence.context, rq->fence.seqno, > > run_status(rq), > > > > Thanks, > > > > > > In any case worst thing should be a panic if the code hits an invalid > > > address before finding a '\0' byte - probably unlikely anyway. > > > > > > I'd fix it, but try to stop it being backported. > > > > > > David > > > > > -- Masami Hiramatsu (Google)