From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f46.google.com (mail-wr1-f46.google.com [209.85.221.46]) (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 3A48A1D5CC8; Tue, 3 Sep 2024 19:16:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725390965; cv=none; b=OioUZwYenJNvnKVOhVWepQ2rtSOTAjQNC+QzIB5HBZuGRaeHqt3WwJXkmBCSEOiDEHx/TLaFyCYPY6wrKs4ehcrVISopYFv0t94TdM8EaI2JwckJo2KqPyztiNeTSmMXY3hRNdfOeZfSuT52NO8rTotpbnQGQ8cGyk85KEphChE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725390965; c=relaxed/simple; bh=pc4D2rTYe3uDu4gL5RzbeVO+XN6Y90tHrqkY1CQHZ8M=; h=From:Date:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VCOgi3bbJqJsCF36vorgBF0i6ZjvlXM5a7QJC+AQr0VpcDkBk0HRgBBrn8cclEV43cDKNEmU90XHeoMsgnRoIbGlw8UBbYcepkTYC57tFgUEJ7o7Qwp6HhfxWQkrDamZJlH+5bnQaRyQjoo3sWDIHfDuIDcwRsef7CQtLN18kGE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=E3J4PAwf; arc=none smtp.client-ip=209.85.221.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="E3J4PAwf" Received: by mail-wr1-f46.google.com with SMTP id ffacd0b85a97d-374c4d4f219so1917036f8f.1; Tue, 03 Sep 2024 12:16:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1725390962; x=1725995762; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=oIKMnKHHdmH0tgNR7Q0mOb34yahsFaU+l95FDBvyAEo=; b=E3J4PAwf9iQNvuarBVXBF/5etkiUbOvE5AEmZwMKkcQz/CVKXX2fw956xZO1iWxJUh 61R4eQfdcQyHing1jTO3MyO9t2GCQYlvBI6E+Qa/C+TxmAW5gV6t4C75wjccOguB8twU YOKSS+ZFpLF/z0UC1OiNFNB9Z9FPalWSNI69Sgr1nu9mSob62i53mZO5PHYrZQXAHOf5 5+fOjhoy5cxzW4Ndi6S4WhRuqRkdrniZ0BGYL4TLTUYg17kVFT2FJp5nhmn2CRp8yBbl Cco10aM0McYvlT5Q7KBAgxeWwK3YtWr+SuuH7BgeWjV5e/iqZw+Qfcg3hekf95Oubu7J ghJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725390962; x=1725995762; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=oIKMnKHHdmH0tgNR7Q0mOb34yahsFaU+l95FDBvyAEo=; b=UINGdxbAC5phovkfUtU/IVtWOAJLgG+nvTsg1yyhQYSf/RG0p2tFw4P9aMnk1f47du hEit63+WZU0U0wREkEPvhoYYTYq/rd7ozoKeETNaNIDCMBAStEW8E+yHqgoHFWaXRrzD 4FOgFt3xXdOEcsELlMMT2LtVH2Rju+t0SqNUv7t6o5N7UZhu4noOreTesLjL1ndFJXvS fzpPuSvxS/lzGVyD0w07sonh8GNiiQjnyWoEpC7tI4zfK6dY61G+/JvpIGDbEqWQQgvh xy09ePVMauJkh5Q7MWBwSxcJOhmhrzfk0r8gBMGOMefw8ubfqMsohhcFzRReBB5Kuh1p V++A== X-Forwarded-Encrypted: i=1; AJvYcCVSzYME2hpebMIxpyBWhrtFxvukSHpdhOW5wQlEiRsBtbI1F+0Wm+knphTRD/EtO8VF7wBXfYCiBGtjYJ6z7FbheBjz@vger.kernel.org, AJvYcCVpmdexVz4TnM+w0NPvwQFIyf0qvr8ljiUCVF579PUpTWrsD9DvQv0gxWcPu0yUcHzONVs=@vger.kernel.org X-Gm-Message-State: AOJu0YzGUCUpoBbUgRdOa40sAD6ALtKUKqwbUSi7KNZmmn9lxnEpinAJ bK43KhHFrdXdu35Q+A/0KQTEG6xJuPl+8lF9EZWN9yPaZjafOBc9 X-Google-Smtp-Source: AGHT+IHlQkyOpufz7x/AQMvhA8sEw5Cq/FXXlpSLlS21HqKGXn7emmi/2SotzMe1MGIisdd46ltNcw== X-Received: by 2002:a5d:59a4:0:b0:368:75:2702 with SMTP id ffacd0b85a97d-374ecc6774bmr4076569f8f.13.1725390962143; Tue, 03 Sep 2024 12:16:02 -0700 (PDT) Received: from krava ([87.202.122.118]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-374c96a88ebsm7029092f8f.108.2024.09.03.12.15.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Sep 2024 12:16:01 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Tue, 3 Sep 2024 22:15:55 +0300 To: Andrii Nakryiko Cc: Jiri Olsa , Oleg Nesterov , Tianyi Liu , Jordan Rome , ajor@meta.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, flaniel@linux.microsoft.com, albancrequy@linux.microsoft.com, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH v2] tracing/uprobe: Add missing PID filter for uretprobe Message-ID: References: <20240830101209.GA24733@redhat.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Sep 03, 2024 at 11:11:06AM -0700, Andrii Nakryiko wrote: SNIP > > Aren't we conflating two things here? Yes, from what Oleg explained, > > it's clear that using task->mm is wrong. So that is what I feel is the > > main issue. We shouldn't use task->mm at all, only task->signal should > > be used instead. We should fix that (in bpf tree, please). > > > > But I don't get the concern about linux->mm or linux->signal becoming > > correction, we shouldn't worry about *linux->signal* becoming NULL. > linux->mm can become NULL, but we don't care about that (once we fix > filtering logic in multi-uprobe). > > > NULL because of a task existing. Look at put_task_struct(), it WILL > > NOT call __put_task_struct() (which then calls put_signal_struct()), > > so task->signal at least will be there and valid until multi-uprobe is > > detached and we call put_task(). > > > > So. Can you please send fixes against the bpf tree, switching to > > task->signal? And maybe also include the fix to prevent > > UPROBE_HANDLER_REMOVE to be returned from the BPF program? ok, it's uprobe-multi specific, let's discuss that over the change itself, I'll try to send it soon jirka > > > > This thread is almost 50 emails deep now, we should break out of it. > > We can argue on your actual fixes. :) > > > > > > > > Oleg suggested change below (in addition to same_thread_group change) > > > to take that in account > > > > > > jirka > > > > > > > > > --- > > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > > > index 98e395f1baae..9e6b390aa6da 100644 > > > --- a/kernel/trace/bpf_trace.c > > > +++ b/kernel/trace/bpf_trace.c > > > @@ -3235,9 +3235,23 @@ uprobe_multi_link_filter(struct uprobe_consumer *con, enum uprobe_filter_ctx ctx > > > struct mm_struct *mm) > > > { > > > struct bpf_uprobe *uprobe; > > > + struct task_struct *task, *t; > > > + bool ret = false; > > > > > > uprobe = container_of(con, struct bpf_uprobe, consumer); > > > - return uprobe->link->task->mm == mm; > > > + task = uprobe->link->task; > > > + > > > + rcu_read_lock(); > > > + for_each_thread(task, t) { > > > + struct mm_struct *mm = READ_ONCE(t->mm); > > > + if (mm) { > > > + ret = t->mm == mm; > > > + break; > > > + } > > > + } > > > + rcu_read_unlock(); > > > + > > > + return ret; > > > } > > > > > > static int