From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B90E53DB336; Fri, 26 Jun 2026 15:45:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782488746; cv=none; b=NZCZr5RBuIx5ap8pwv67ZYF3chmXMc8cQITNoKMYlLJDO10YFHino6Ye4FPlRM4QtyM4an/Q3pusEdYXlKp2Rk5cQF+rnjV9FvNxqHwyrVeKxpSx0UAozVnvVZjz8KNZ0p3mP64s5EfX8l3Usaai6/PJP7o2VAotttmP3I+O2VQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782488746; c=relaxed/simple; bh=qZKptdCJSkMTTyABot2IPcwQP8mWC4AcZQJO2SalZCY=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=B4ABxozuw88AOHwpHEeWi0Aiuosu7KXLj6ohXKzwt9CQuG9jYWe4HTNsNyQC8nz3MFd1azl58PAOquQn9nftSocUy00WHNDpWDcP4BoPa7OAvv0XEkxLbGabe39JFm1l4kR+6mBoqZRruolLGTkLQO+0xlYdqZHKINxYPA2EaeA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VC7qYdhV; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VC7qYdhV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7C7691F000E9; Fri, 26 Jun 2026 15:45:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782488741; bh=5nNXMDWDKH1yXvqBFyPzRpjFWZl62kKodd/S4IBn1Ns=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=VC7qYdhVzne83s+YIAuvUw/NmYE9soPzXB4P2iVw55hOY+jO4CyYTCyeVepIx8l9H Cvlk7Npk3OTX96bITvLGN8G3ug/rt2eYlsx4m1vpUS9GbFhbCqUrUTlx0dSUMKg246 oLWm32k2CKgtCJvZDsR1mQ1VQubzZmVz4bvZARQzRJMLpfQK5bhe5b0gt7xYaBesVa 9q6DAaKqi1KnwYjnPJYyVYRJ/Kk0SgTABl6lSMavU3nEnZsbeBgsCyjJ4MIRkyDx2v /jaWzYkWrDvuDy9vf+Ia2izcQLSaRqR4d9uZyFI07ErfKG6MCbZE3NlYMLwprHQdvq cgBt5DwvcteRQ== Date: Sat, 27 Jun 2026 00:45:38 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Martin Kaiser , "Masami Hiramatsu (Google)" , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tracing: eprobe: read the complete FILTER_PTR_STRING pointer Message-Id: <20260627004538.4cc8b34a4a20ee14f9a38c28@kernel.org> In-Reply-To: <20260626064223.60ffeeaa@fedora> References: <20260615145500.2662456-1-martin@kaiser.cx> <20260616110910.e6420488b6a798d49951cde9@kernel.org> <20260618105227.c58c85e9cb19bce673d9a79b@kernel.org> <20260622125815.7416792c020bd3d81c01e51b@kernel.org> <20260626055440.76c28d25@fedora> <20260626064223.60ffeeaa@fedora> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-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 Fri, 26 Jun 2026 06:42:23 -0400 Steven Rostedt wrote: > On Fri, 26 Jun 2026 12:20:36 +0200 > Martin Kaiser wrote: > > > > That is, to have +u0() say "this is going to be dereferencing user space". > > > > > I'll add Martin's patch and see if it makes the above work. > > > > I've just tried your command with my patch. It works for me, filenames are > > logged correctly. > > Yep, this definitely looks like a fix. We have; > > addr = rec + field->offset; > > Where addr points to the location of the field on the ring buffer, thus > your change to make it: > > val = *(unsigned long *)addr; > > Reads the full "long size" of the event on the ring buffer, instead of > reading just one byte. It is "val" that gets dereferenced later by the > probe logic (the "+0u()"), which has all the protections we need. > > I'll queue this up. I've already queued this on my probes/core branch. (which will be probes/fixes) Thanks, > > Thanks! > > -- Steve -- Masami Hiramatsu (Google)