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 5B1B92FB969; Mon, 16 Feb 2026 08:00:07 +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=1771228807; cv=none; b=Zss6v8XTC56aP8lLziRGePy2Wp1eS7ATzONNB3G/koZL6hFbgnITksbd9CcLw3DkqHkYLGRKIZq00fYsMgPmbVtZ3NeQV2K0brgpcReUFGF0fB3ngRGAWTppaPogOJmfmfYaz83DJPg8lrycrm7hg2qU1c7JLIHCHWxC+UI8T2c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771228807; c=relaxed/simple; bh=awGVTKCHiUkewonOwODdZbQc3D1dA6XfSifeCZovq9M=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=UEplLHFXRlVYbZPKLVrtUHKsu916jJuwiAIGUqf5XHm9kiDop41p9okmge3Q3G2R0mx9h/gSgQe6t3YRXs86yxn/vvbIHkHCYxb89U+9JaLS5MdgGCZyA0c5FBurdOaNUJ9lhF6npjIna9OCDDBpkYszahuZ9D82KdRDUDl1mIY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fjIxCfwI; 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="fjIxCfwI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 967F7C116C6; Mon, 16 Feb 2026 08:00:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771228806; bh=awGVTKCHiUkewonOwODdZbQc3D1dA6XfSifeCZovq9M=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=fjIxCfwIH3eZM5lgA5oIv+ha0/cR/gZ8U234L4t79KsSOkw4F4juY+wOcoxt+bnNZ w0VgNYerXKzvMmIHFzdMkSWKdnWfuMKFS/Q3cYIj/ovr+fkWgPwyFo6nUCmhg1v0s/ W9+zRuUwISWmFr3ED9CI9Ewf8F5ahUdwsHQxEvfxdFjLs4AyG+yg1aacB10sn2DVPO vNztG1MjtylXogVBPyX/V39bE3pI42Ca08aZ/Q6pzgLrSl/HriflWde/gDoRFGUKta HacLaHQ2vPB7OdOqq0CYHK8e1nA+5ro19sSFuTgYyTtNSd8pWjVHyiTG+25uLriHDt Z3Cbko10RdMqA== Date: Mon, 16 Feb 2026 17:00:01 +0900 From: Masami Hiramatsu (Google) To: Daniil Dulov Cc: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , "open list:TRACING" , "open list:TRACING" , , "kernel test robot" , Dan Carpenter Subject: Re: [PATCH] ring-buffer: Fix possible dereference of uninitialized pointer Message-Id: <20260216170001.f6d362ab74f47d2e888b4947@kernel.org> In-Reply-To: <20260213100130.2013839-1-d.dulov@aladdin.ru> References: <20260213100130.2013839-1-d.dulov@aladdin.ru> 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, 13 Feb 2026 13:01:30 +0300 Daniil Dulov wrote: > There is a pointer head_page in rb_meta_validate_events() which is not > initialized at the beginning of a function. This pointer can be dereferenced > if there is a failure during reader page validation. In this case the control > is passed to "invalid" label where the pointer is dereferenced in a loop. > > To fix the issue initialize orig_head and head_page before calling > rb_validate_buffer. > > Found by Linux Verification Center (linuxtesting.org) with SVACE. > Looks good to me. Acked-by: Masami Hiramatsu (Google) Thanks! > Reported-by: kernel test robot > Reported-by: Dan Carpenter > Closes: https://lore.kernel.org/r/202406130130.JtTGRf7W-lkp@intel.com/ > Fixes: 5f3b6e839f3c ("ring-buffer: Validate boot range memory events") > Signed-off-by: Daniil Dulov > --- > kernel/trace/ring_buffer.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 630221b00838..ad08430347b0 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -1918,6 +1918,8 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) > if (!meta || !meta->head_buffer) > return; > > + orig_head = head_page = cpu_buffer->head_page; > + > /* Do the reader page first */ > ret = rb_validate_buffer(cpu_buffer->reader_page->page, cpu_buffer->cpu); > if (ret < 0) { > @@ -1928,7 +1930,6 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) > entry_bytes += local_read(&cpu_buffer->reader_page->page->commit); > local_set(&cpu_buffer->reader_page->entries, ret); > > - orig_head = head_page = cpu_buffer->head_page; > ts = head_page->page->time_stamp; > > /* > -- > 2.34.1 > > -- Masami Hiramatsu (Google)