From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) (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 EFDB91388 for ; Wed, 13 Nov 2024 04:32:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731472359; cv=none; b=OUywYyE4zPCFJX0xRfc6NKIZX+B5pvqZW4eZSgDlNv+XrqATgsuX0uMCi7QN6cUDlxA6NOlhd0UCaBxdjunnAgotHIIvCl9HEiWFC0zOjwnXZLN7onv1Y4W5mucMhZKDe9n0RvbxfkWvaaMeAMpZm9jS+WTSyieb+KpWnvZL9P8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731472359; c=relaxed/simple; bh=haRrDsJ2aUtJWtMOxmMasdOLu2DaInUijUDQk48Kc0k=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=m4tFBlg06PtOD1eiCa5KqxV4X1O0/mtS3tHUFT+vL4E3v+cXRL0drmNBAaSCfzbgUXd5je6J/Vg/SyCrlrwGDk4nb2kduIAKdii4fRQI2ctXszk19I1PPMa4v50z67BcJgi0CHdn8GCQSJvVgP4kShV/Q0NCOxAOjF+H7rs7Dx4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=CUlyyXNo; arc=none smtp.client-ip=91.218.175.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="CUlyyXNo" Message-ID: <94e85972-ec2f-4231-bf0a-fcdda0ebde57@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1731472354; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tVjFpZOzvpDYD92WuPEcFMkP4peps0TrT1iwKMSrYAE=; b=CUlyyXNo10mgVLESGxHCN9cjIgiLQRrM49XKRdBQJxP75lmhpBNwXVgHH5rM2LlNT6wB5N Hp54VRvV8CrpTdAr4pT7UVM8Nv1PDSTLTPnV0C4mH8L0oHBgzjpM+I5+8ctJ8CwNDT3dNq SIc0L6e7zIq5MqJ4tFh4FHQ+wGZ5Vpc= Date: Tue, 12 Nov 2024 20:32:27 -0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v12 4/7] bpf, x86: Support private stack in jit Content-Language: en-GB To: Alexei Starovoitov Cc: bpf , Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Kernel Team , Martin KaFai Lau , Tejun Heo References: <20241112163902.2223011-1-yonghong.song@linux.dev> <20241112163922.2224385-1-yonghong.song@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 11/12/24 5:13 PM, Alexei Starovoitov wrote: > On Tue, Nov 12, 2024 at 8:41 AM Yonghong Song wrote: >> + >> +static void priv_stack_check_guard(void __percpu *priv_stack_ptr, int alloc_size, >> + struct bpf_prog *prog) >> +{ >> + int cpu, underflow_idx = (alloc_size - PRIV_STACK_GUARD_SZ) >> 3; >> + u64 *stack_ptr; >> + >> + for_each_possible_cpu(cpu) { >> + stack_ptr = per_cpu_ptr(priv_stack_ptr, cpu); >> + if (stack_ptr[0] != PRIV_STACK_GUARD_VAL || >> + stack_ptr[underflow_idx] != PRIV_STACK_GUARD_VAL) { >> + pr_err("BPF private stack overflow/underflow detected for prog %sx\n", >> + bpf_get_prog_name(prog)); >> + break; >> + } >> + } >> +} > I was tempted to change pr_err() to WARN() to make sure this kinda bug > is very obvious, but left it as-is. > I think kasan-ing JITed load/stores and adding poison to guards > will be a bigger win. > The bpf prog/verifier bug will be spotted right away instead of > later during jit_free. Agree. I will work on this as a follow-up.