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 2ADEF1643F for ; Tue, 11 Jul 2023 07:26:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5956EC433C8; Tue, 11 Jul 2023 07:26:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689060367; bh=7gagTghnHbdnS89ft0SRPtMAku+GMOo4ENlpz1jSnaY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Y5D8O/k6Bv2j9KFP/x+I+2+38XTL83NpDNhCVx0vQIE3mGkCesQJn7itmiRafmHGf kLdZBa0YUc5ct+Yras8ghAFIRFYwg3LGi+FUM5gWESTbBha0QeaRK01y7OPxoqxSfK WOGMbDGr5hIjSIhA163abe6dBNc8nmeKXoDEE0EEAcXokMZTPBHyiIqKBXS7yghK6T LSS77lIMXAbF7j0nKV7fzLjJS/Jey+NC8542G4E/IV0eabznx0eVKw4uivUHUKT5wn ui39sNIxswdxahuME4wLO8DKg++S7VG9Qe++P6vib6MEsoF0Z/pvBljiFm2bjHdNq3 h+BiIXwlIavxg== Date: Tue, 11 Jul 2023 10:26:03 +0300 From: Leon Romanovsky To: Krister Johansen Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Shay Agroskin , Arthur Kiyanovski , David Arinzon , Noam Dagan , Saeed Bishara , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Subject: Re: [PATCH net] net: ena: fix shift-out-of-bounds in exponential backoff Message-ID: <20230711072603.GI41919@unreal> References: <20230711013621.GE1926@templeofstupid.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230711013621.GE1926@templeofstupid.com> On Mon, Jul 10, 2023 at 06:36:21PM -0700, Krister Johansen wrote: > The ENA adapters on our instances occasionally reset. Once recently > logged a UBSAN failure to console in the process: > > UBSAN: shift-out-of-bounds in build/linux/drivers/net/ethernet/amazon/ena/ena_com.c:540:13 > shift exponent 32 is too large for 32-bit type 'unsigned int' > CPU: 28 PID: 70012 Comm: kworker/u72:2 Kdump: loaded not tainted 5.15.117 > Hardware name: Amazon EC2 c5d.9xlarge/, BIOS 1.0 10/16/2017 > Workqueue: ena ena_fw_reset_device [ena] > Call Trace: > > dump_stack_lvl+0x4a/0x63 > dump_stack+0x10/0x16 > ubsan_epilogue+0x9/0x36 > __ubsan_handle_shift_out_of_bounds.cold+0x61/0x10e > ? __const_udelay+0x43/0x50 > ena_delay_exponential_backoff_us.cold+0x16/0x1e [ena] > wait_for_reset_state+0x54/0xa0 [ena] > ena_com_dev_reset+0xc8/0x110 [ena] > ena_down+0x3fe/0x480 [ena] > ena_destroy_device+0xeb/0xf0 [ena] > ena_fw_reset_device+0x30/0x50 [ena] > process_one_work+0x22b/0x3d0 > worker_thread+0x4d/0x3f0 > ? process_one_work+0x3d0/0x3d0 > kthread+0x12a/0x150 > ? set_kthread_struct+0x50/0x50 > ret_from_fork+0x22/0x30 > > > Apparently, the reset delays are getting so large they can trigger a > UBSAN panic. > > Looking at the code, the current timeout is capped at 5000us. Using a > base value of 100us, the current code will overflow after (1<<29). Even > at values before 32, this function wraps around, perhaps > unintentionally. > > Cap the value of the exponent used for this backoff at (1<<16) which is > larger than currently necessary, but large enough to support bigger > values in the future. > > Cc: stable@vger.kernel.org > Fixes: 4bb7f4cf60e3 ("net: ena: reduce driver load time") > Signed-off-by: Krister Johansen > --- > drivers/net/ethernet/amazon/ena/ena_com.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c > index 451c3a1b6255..633b321d7fdd 100644 > --- a/drivers/net/ethernet/amazon/ena/ena_com.c > +++ b/drivers/net/ethernet/amazon/ena/ena_com.c > @@ -35,6 +35,8 @@ > > #define ENA_REGS_ADMIN_INTR_MASK 1 > > +#define ENA_MAX_BACKOFF_DELAY_EXP 16U > + > #define ENA_MIN_ADMIN_POLL_US 100 > > #define ENA_MAX_ADMIN_POLL_US 5000 > @@ -536,6 +538,7 @@ static int ena_com_comp_status_to_errno(struct ena_com_admin_queue *admin_queue, > > static void ena_delay_exponential_backoff_us(u32 exp, u32 delay_us) > { > + exp = min_t(u32, exp, ENA_MAX_BACKOFF_DELAY_EXP); Thanks, Reviewed-by: Leon Romanovsky