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From: "Min Hu (Connor)" <humin29@huawei.com>
To: Gaëtan Rivet <grive@u256.net>
Cc: <chas3@att.com>, <declan.doherty@intel.com>, <dev@dpdk.org>,
	<gowrishankar.m@linux.vnet.ibm.com>, <stable@dpdk.org>
Subject: Re: [dpdk-dev] [v1, 2/2] bonding: fix PCI address comparison on non-pci ports
Date: Wed, 16 Dec 2020 20:14:53 +0800
Message-ID: <447435c6-e04f-ab63-695b-8d46827a141b@huawei.com> (raw)
In-Reply-To: <20201207140711.3mjklkmkjrfwts5g@u256.net>

     sorry for late reply.
     I know what you mean. But "find_port_id_by_pci_addr"
is one static type funtion. it is only used in the function
"parse_port_id". what you modified in "find_port_id_by_pci_addr"
is totally done before "find_port_id_by_pci_addr" in the function
"parse_port_id". That is, it first find pci_bus, then find
rte_pci_device, at last get port id.
So the bug you described will not happen in current version,
unless others directly use the function "find_port_id_by_pci_addr"
without considering that rte_eth_devices[] may contain non-pci devices.

So, I think the patch is OK to me.

Acked-by: Min Hu (Connor) <humin29@huawei.com>

在 2020/12/7 22:07, Gaëtan Rivet 写道:
> On 26/11/20 10:24 +0800, Min Hu (Connor) wrote:
>> what scenarios may cause bugs in old ways.
>> Could you give an example, thanks.
> Hello,
> For example in the following code:
> -       RTE_ETH_FOREACH_DEV(i) {
> -               pci_dev = RTE_ETH_DEV_TO_PCI(&rte_eth_devices[i]);
> -               eth_pci_addr = &pci_dev->addr;
> All ethdev are iterated, before reading their supposed PCI addresses, and
> comparing those to the one passed in arguments.
> But not all ethdev will be PCI devices, so the cast is incorrect. It will do
> a containerof() on a structure that it supposes contains an rte_device at the
> offset 16 (two pointers accounting for the TAILQ_ENTRY()), but nothing prevents any
> other bus from implementing their device with any other layout.
> So the cast is wrong, but generally it will give out readable memory at least.
> Then the field ((eth_dev)->device)->addr will be read and compared against the input,
> with arbitrary data here.
> A scenario that could cause bug would be when another bus implements a device
> in such a way that it will write plausible binary rep of PCI addresses at the
> same offset, and match a request from a user. The bonding PMD would take the
> device over without properly checking that it is actually a PCI device.
> There have been APIs introduced in the EAL to simplify the iteration of
> devices, especially restricted to buses. Those APIs should be used instead.
> The current implementation is inefficient and wrong. It will work in most cases
> but can still trigger weird issues for users, especially in cases that bonding
> PMD devs won't generally encounter (with setups where multiple buses are used
> with a variety of devices).
> Regards,

  reply	other threads:[~2020-12-16 12:15 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-17 16:42 [dpdk-dev] [PATCH v1 0/2] bonding: fix port id check and PCI addr cmp Gaetan Rivet
2020-04-17 16:42 ` [dpdk-dev] [PATCH v1 1/2] bonding: fix port id validity check on parsing Gaetan Rivet
2020-11-26  2:45   ` [dpdk-dev] [PATCH v1, " Min Hu (Connor)
2020-12-07 13:34     ` Ferruh Yigit
2020-04-17 16:42 ` [dpdk-dev] [PATCH v1 2/2] bonding: fix PCI address comparison on non-pci ports Gaetan Rivet
2020-11-26  2:24   ` [dpdk-dev] [v1, " Min Hu (Connor)
2020-12-07 14:07     ` Gaëtan Rivet
2020-12-16 12:14       ` Min Hu (Connor) [this message]
2020-12-17 10:53         ` [dpdk-dev] [dpdk-stable] " Ferruh Yigit

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