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 5A8CB156225; Wed, 18 Dec 2024 13:17:24 +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=1734527844; cv=none; b=P06IZUPUiSuTongqt4GQWhkevVV7Gdza5xwz0/VaKe0pv27RxXd3bjUwy+15X4Jh5XHtdMwyDj6crZqrpZsQsQkseGoBW7Pf2IlGDXiXeZ9v5f6IsDBkVHhQMiFYxqqMuOipfhGR3GGL88LC+osIKuTZ5sUdQFMJkbUJdjEKlas= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734527844; c=relaxed/simple; bh=nDtxIcUdvyI/ltjZ2KqovuX6yrx2/7dNovXbDvQWnCQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Aefd5o7dAlEZLfPWAnOdz46P0B6KzvpuV6N0ijfe504witwqEv+oKRfZohwZomX69lidFsD0lDlJ+XS+dQZ5I8kFuWpM+CQef4SXmmd7jOs3rIDrPOXKrVZeHX0H7x1/VeJYhgWYDuDr9H/u/rer4nukQNt7bVUVoPaP9fxeWhI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0EE5C4CEDD; Wed, 18 Dec 2024 13:17:22 +0000 (UTC) Date: Wed, 18 Dec 2024 08:18:00 -0500 From: Steven Rostedt To: Edward Adam Davis Cc: vdonnefort@google.com, aha310510@gmail.com, david@redhat.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, mhiramat@kernel.org, syzbot+345e4443a21200874b18@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com Subject: Re: [PATCH V2] ring-buffer: fix overflow in __rb_map_vma Message-ID: <20241218081800.05d81fe4@gandalf.local.home> In-Reply-To: References: X-Mailer: Claws Mail 3.20.0git84 (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 Wed, 18 Dec 2024 19:42:22 +0800 Edward Adam Davis wrote: > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 7e257e855dd1..20f0e01b7a50 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -7019,7 +7019,11 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, > lockdep_assert_held(&cpu_buffer->mapping_lock); > > nr_subbufs = cpu_buffer->nr_pages + 1; /* + reader-subbuf */ > - nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ > + nr_pages = ((nr_subbufs + 1) << subbuf_order); /* + meta-page */ > + if (nr_pages < pgoff) That probably should be <= as if it was equal... > + return -EINVAL; > + > + nr_pages -= pgoff; nr_pages would be zero and > > nr_vma_pages = vma_pages(vma); > if (!nr_vma_pages || nr_vma_pages > nr_pages) this would return true, which the next line is: return -EINVAL; Why not catch it before going through all that? -- Steve > --