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dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=goodmis.org header.i=@goodmis.org header.a=rsa-sha256 header.s=dkim1 header.b=ozFpx+Tn Received: from omf16.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 97AC3120860; Mon, 26 Oct 2026 19:38:49 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf16.hostedemail.com (Postfix) with ESMTPA id B9CF420013; Mon, 26 Oct 2026 19:38:47 +0000 (UTC) Date: Mon, 26 Oct 2026 15:38:46 -0400 From: Steven Rostedt To: "Masami Hiramatsu (Google)" Cc: Shuah Khan , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH 04/10] tracing/filters: Handle out-of-range CPU for OP_NE in cpumask comparison Message-ID: <20261026153846.672c760e@gandalf.local.home> In-Reply-To: <179285916115.466249.16061782430177051612.stgit@devnote2> References: <179285912318.466249.7425922682086130057.stgit@devnote2> <179285916115.466249.16061782430177051612.stgit@devnote2> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamout06 X-Stat-Signature: 64t3e63arizw83rcbc5fx5s75m9wrc9d X-Rspamd-Queue-Id: B9CF420013 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX18EbIdT0THeRj4MNb530kbySwriKu0IMtI= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=goodmis.org; h=date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; s=dkim1; bh=IG6lC5VmLeqP65oSAtdAx1VbFAtk7d9g8bHTWsFni2o=; b=ozFpx+Tn95HddNuk6ZaCvSoh43etYOsqebLGMZVg+4agvzInce5r/nN7WfNVJGS5YVwUsoaDPKt4HAmaTQEkT8mVvOqJiWRRAbfXTOK0fSyMzdW4R0mbLTZEoyAQBb0UBHsxizGeOVJVR7P3fE/SjoNAkRz8H1Fyjiot3sZ4Ang= X-HE-Tag: 1793043527-359451 X-HE-Meta: U2FsdGVkX1+ADCmTBohVlg/PkjfzLah0vItZkBRMDzproUuHADahppCw+HPRpzy8Pm2UEfwxrBq90944zVeIRbrEHo/EIu0ZiX/NMwYwNtDngv4XlcUzI7JZpfSgLTmpiT3xwMdsmhThdD5OEJ0Xo2ocg8IPTNxPr2Q0P35Ot86ykFYYOLeUvCbid4ubF82C9lbAM3DsQBXEjYgjpPFoo4Jc4F1CBezvv+iMRBumH6QuCdgXMvb+4h0v7seRzKIEPeaWbbN8iLwJM3clkoxr4okbfW/Si3B4KmIHAFIuIB75n3Y4OyJAdwUnBcuSLwGT1/piS3aXPFjiAAFM52jNWGFNMOWO+38j On Sun, 25 Oct 2026 01:26:01 +0900 "Masami Hiramatsu (Google)" wrote: > From: Masami Hiramatsu (Google) > > In filter_pred_##size##_cpumask(), if the event's scalar CPU value is > out of range (cpu >= nr_cpu_ids), it unconditionally returns 0. > > However, if the predicate operation is OP_NE (e.g., field != CPUS{0,1}), > an out-of-range CPU cannot match any valid CPU in the user-provided > cpumask and the condition is satisfied. Returning 0 produces a false > negative. > > Return "pred->op == OP_NE" instead of 0 when cpu >= nr_cpu_ids. > > Fixes: 3cbec9d7b93d ("tracing/filters: Enable filtering a scalar field by a cpumask") > Cc: stable@vger.kernel.org BTW, a lot of these are just "stupid input produces stupid results" and I personally feel it doesn't deserve a stable tag. I don't even think it deserves the "fixes" tag. Now if the stupid input were to produce a crash or warning, then that's different. -- Steve > Signed-off-by: Masami Hiramatsu (Google) > --- > kernel/trace/trace_events_filter.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c > index 69da95f42541..d9aeeec4ed91 100644 > --- a/kernel/trace/trace_events_filter.c > +++ b/kernel/trace/trace_events_filter.c > @@ -762,7 +762,7 @@ static int filter_pred_##size##_cpumask(struct filter_pred *pred, void *event) \ > unsigned int cpu = *addr; \ > \ > if (cpu >= nr_cpu_ids) \ > - return 0; \ > + return pred->op == OP_NE; \ > \ > return do_filter_scalar_cpumask(pred->op, cpu, pred->mask); \ > }