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 8DF7535F60F; Wed, 29 Jul 2026 23:54:28 +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=1785369269; cv=none; b=NI0rfEvNMvDreAlEOTc0szUjRKbr7bwg/QrmAb20gZzBFKU1c/K5Wnh4sEmMYIwvPE8Wx5o5X/7nQXghJXgKjet0nh7qChWniWLch7wyja+eLVXfhy32GbqvHJPlVHFUU2LrNKiFMYVhDGZGx+tQNLVOqOwZPQ5tlJNMn77Wbtk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785369269; c=relaxed/simple; bh=mk0ysuQeVKrkFHWAAQe9lU/hLVqzePR/R1QAUuh8rP0=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=nPKDnrbeYazfvK92L8iyEzkCS0q5YgnN3t+i1FRGwD6nxV/0/Mrtx9m/PQYIfGouStKDdAAKa+ZwLR6DXbiaxGkVw71c26qFEUH4+TuYQueDPuDV3f43OsU+PLHfeeeSaSAI5Y2h0VYV+qv6mveyvna0agY5HArTn07/23eUf5g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U3AcRQA9; 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="U3AcRQA9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA6F71F000E9; Wed, 29 Jul 2026 23:54:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785369268; bh=S4i1MKc4I4+9ayCuIhJnqaUS/QxUEZoRrMHVFl5plEg=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=U3AcRQA9/oI4tUSq1anW24dD1dbCZkK61nJ6+d2dHzhGH7dF+qy3SoWte2menLjEb 0QhcdfK0wkG/qwt3Gm93P0I+A1f/ybfhLYecKG3hVip2UULAzp8vUKn0nUrzbkX+FR r6h018Ja1rJk5D3/T3LBm+9ZYeQz+AYpivdzNYx6F9kRG0Wi6aIBkdLSCEONZ09BNW yZOehJ5tU9yEwLKg59aIGRAlFqu2U340ix+jKB7lDdJnQ4mm3Ab/MuGKVjzYY0vM36 9S/lBhtSSOwVO6b5+T4W+9ScULxwBc046GQjcu4ICrk0KgYHPrdd2+W/DzsciPO8kt saWxHjd0Epvfg== Date: Thu, 30 Jul 2026 08:54:21 +0900 From: Masami Hiramatsu (Google) To: Andrii Nakryiko Cc: Oleg Nesterov , Breno Leitao , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Masami Hiramatsu , Andrii Nakryiko , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, kernel-team@meta.com, stable@vger.kernel.org Subject: Re: [PATCH] uprobes: Fix NULL pointer dereference in hprobe_expire() Message-Id: <20260730085421.d455361164695270bd764a4b@kernel.org> In-Reply-To: References: <20260729-uprobe-v1-1-61896b87c867@debian.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Wed, 29 Jul 2026 12:31:08 -0700 Andrii Nakryiko wrote: > On Wed, Jul 29, 2026 at 9:02 AM Oleg Nesterov wrote: > > > > On 07/29, Breno Leitao wrote: > > > > > > --- a/kernel/events/uprobes.c > > > +++ b/kernel/events/uprobes.c > > > @@ -832,7 +832,7 @@ static struct uprobe *hprobe_expire(struct hprobe *hprobe, bool get) > > > if (try_cmpxchg(&hprobe->state, &hstate, uprobe ? HPROBE_STABLE : HPROBE_GONE)) { > > > /* We won the race, we are the ones to unlock SRCU */ > > > __srcu_read_unlock(&uretprobes_srcu, hprobe->srcu_idx); > > > - return get ? get_uprobe(uprobe) : uprobe; > > > + return get && uprobe ? get_uprobe(uprobe) : uprobe; > > > > Well, looks "obviously correct". At least the current code is obviously > > wrong, it even checks uprobe != NULL 3 lines above. > > > > Andrii ? > > > > Yes, indeed, I'm more surprised this didn't come up much earlier > (probably it's rare enough to have uretprobe with refcnt at zero > during fork). The fix looks good, thanks! > > Acked-by: Andrii Nakryiko > > > Acked-by: Oleg Nesterov > > Thanks, this seems good to me. (uprobe is NULL checked in try_cmpxchg(), so it could be NULL.) Can I pick this to probes/fixes branch? Thank you, -- Masami Hiramatsu (Google)