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 A3BF74CF499; Sun, 18 Oct 2026 14:01:26 +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=1792332087; cv=none; b=rqBqVK1jz06mLNR9PmKa7ZASK+EaiuQIBQ0FLhTWUfHVEhX7aPYvChozfVNLk5mLE60Z/xyWFzW5V2zzHkz8Zsa0qR+vSqJCui3W1rZRmct0PdJHrxLKN5WqyVljurK/xWvNylSlG0E8PJU2GL1CjJVO/jOjB6kJdtyH0eRPDLI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792332087; c=relaxed/simple; bh=X/tZPcIcG5b5lbGINhooOKXr3pcp5Fse4ENDDkF5c5k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=HjTrWuUnOJaIhV0iEhFA6ELIX6Oes8jealb3Q3YSR+UvuJPpgsy8CIKR72yBtJuNZVNHq3D611C/SpUcxn+k+8zp7/g90J9FVyiU6VW2RgKzDZDzILgujNcPP5VRYfhe23A18JHOWe3YK/0wVZDm71x9RPiF2Wqk5OAS10zlasw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M7g3SqZN; 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="M7g3SqZN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D09D1F000C4; Sun, 18 Oct 2026 14:01:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792332086; bh=1A30M50E1/c1dVJn3Z1v4PZSDvPxoNJCbANPRlKw/SY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=M7g3SqZN+uA7MiWS/yJuI6RQBk69bDELmgY+ybiQLbbUOPmgWUVt3WpOibqX4dN7B EwvNhCvhaoUoqm5hF561N9PAMjk183fvHQPJMbS39qgGxCwbo/4+DPhNvRqWuE+db8 0+ZUW5Y+9YS71hCUKxFsK7B2JSZiNZOXOdxjWh2/fmy6LROzXIgsGM+V9h/T2YwwiT rSDaRq9iX1r9YrVvi3DsK8P6dNcg74HK6S73HdDw3heSppMq6aV1HTgMF1jlrE4jYf r0zFYHkUBj9MsbR16zvu9bhSk5VRt4UiJ8eDVw/iITQ+vqDCdc47geCZ/Nf1KxS5hX 22a3dNcD+n3Cg== Date: Sun, 18 Oct 2026 15:01:20 +0100 From: Simon Horman To: Vaibhav Nagare Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, michael.chan@broadcom.com, pavan.chebbi@broadcom.com, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, andrew+netdev@lunn.ch, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, nagarevaibhav@gmail.com, stable@vger.kernel.org Subject: Re: [PATCH net v4] bnxt_en: don't leave an XDP program installed when the open fails Message-ID: <20261018140120.GJ503057@horms.kernel.org> References: <20261012072802.2153706-1-vnagare@redhat.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: <20261012072802.2153706-1-vnagare@redhat.com> On Mon, Oct 12, 2026 at 12:58:02PM +0530, Vaibhav Nagare wrote: > bnxt_xdp_set() stores the new program and drops the reference on the old > one before reopening the NIC. If bnxt_open_nic() then fails, ndo_bpf() > returns an error with the new program still in bp->xdp_prog. The caller > treats the error as "nothing was installed" and drops its own reference, > so bp->xdp_prog is left pointing at a freed program and the next XDP > update dereferences it: > > BUG: unable to handle page fault for address: ff78ecc80ddd1038 > RIP: 0010:__bpf_prog_put+0x5/0x80 > Call Trace: > bnxt_xdp_set+0xad/0x1b0 [bnxt_en] > dev_xdp_propagate+0x36/0xa0 > bond_xdp_set+0xeb/0x2d0 [bonding] > dev_xdp_install+0x1b1/0x350 > bpf_xdp_link_update+0xc5/0x1b0 > link_update+0x104/0x1e0 > __sys_bpf+0x662/0xcf0 > > Seen on a 6.12 based kernel after bnxt_alloc_mem() failed an order-4 > allocation on a fragmented host: > > bnxt_en 0000:a0:00.1 ens4f1np1: nic open fail (rc: fffffff4) > bond1: (slave ens4f1np1): Error -12 calling ndo_bpf > > Bonding is not required to hit this; a plain XDP attach on a bnxt > interface takes the same path. > > Restore the previous program when an attach or a replace fails, and > recompute the page-mode and XDP TX ring configuration from it. The > configuration matters because bnxt_init_one_rx_ring() only assigns > rxr->xdp_prog in page mode, and __bnxt_set_rx_skb_mode() derives > dev->max_mtu from the installed program. Release the old program only > once the change has been committed. > > A detach is not undone. dev_xdp_detach_link() clears the core's record > of the program even when the driver returns an error, so putting the > program back would leave the driver running a program the core has > already dropped. If the reopen fails during a detach, bnxt_xdp_set() > therefore returns 0 with the device closed; bnxt_open_nic() has already > logged the failure. > > Found in a crash dump; the change was not tested on hardware. > > Fixes: c6d30e8391b8 ("bnxt_en: Add basic XDP support.") > Cc: stable@vger.kernel.org > Signed-off-by: Vaibhav Nagare > --- > v4: > - no functional change. Correct the comment and commit message: the > core clears its record of the program on a failed detach, it does > not drop a reference itself, and note that a failed reopen during a > detach returns 0 with the device closed (Sashiko AI review) > - the same review notes the rollback does not restore the RX > aggregation-ring mode. That is real but pre-existing: without this > patch the failed attach leaves the same bp->flags behind and the > next open fails the same way. Restoring it needs a snapshot of > bp->flags, the LRO/GRO_HW feature bits and the ring parameters, > which is a separate change for net-next > - v3: https://lore.kernel.org/netdev/20261001142516.1386525-1-vnagare@redhat.com/ > - v2: https://lore.kernel.org/netdev/20260930070901.1218980-1-vnagare@redhat.com/ > - v1: https://lore.kernel.org/netdev/20260928131458.1012180-1-vnagare@redhat.com/ Reviewed-by: Simon Horman