DPDK patches and discussions
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From: Thomas Monjalon <thomas@monjalon.net>
To: Akhil Goyal <akhil.goyal@nxp.com>,
	"Yigit, Ferruh" <ferruh.yigit@intel.com>,
	"Trahe, Fiona" <fiona.trahe@intel.com>
Cc: David Marchand <david.marchand@redhat.com>,
	Anoob Joseph <anoobj@marvell.com>,
	"Kusztal, ArkadiuszX" <arkadiuszx.kusztal@intel.com>,
	"dev@dpdk.org" <dev@dpdk.org>,
	"Richardson, Bruce" <bruce.richardson@intel.com>,
	"nhorman@tuxdriver.com" <nhorman@tuxdriver.com>,
	"Mcnamara, John" <john.mcnamara@intel.com>,
	"dodji@seketeli.net" <dodji@seketeli.net>,
	Andrew Rybchenko <arybchenko@solarflare.com>,
	"Trahe, Fiona" <fiona.trahe@intel.com>,
	aconole@redhat.com
Subject: Re: [dpdk-dev] [PATCH v2 4/4] add ABI checks
Date: Sun, 02 Feb 2020 14:05:56 +0100	[thread overview]
Message-ID: <1779027.taCxCBeP46@xps> (raw)
In-Reply-To: <MWHPR11MB18075D79751CE8F99FAF9E56E4070@MWHPR11MB1807.namprd11.prod.outlook.com>

31/01/2020 15:16, Trahe, Fiona:
> On 1/30/2020 8:18 PM, Thomas Monjalon wrote:
> > 30/01/2020 17:09, Ferruh Yigit:
> > > On 1/29/2020 8:13 PM, Akhil Goyal wrote:
> > > >  
> > > > I believe these enums will be used only in case of ASYM case which is experimental.
> > >
> > > Independent from being experiment and not, this shouldn't be a problem, I think
> > > this is a false positive.
> > >
> > > The ABI break can happen when a struct has been shared between the application
> > > and the library (DPDK) and the layout of that memory know differently by
> > > application and the library.
> > >
> > > Here in all cases, there is no layout/size change.
> > >
> > > As to the value changes of the enums, since application compiled with old DPDK,
> > > it will know only up to '6', 7 and more means invalid to the application. So it
> > > won't send these values also it should ignore these values from library. Only
> > > consequence is old application won't able to use new features those new enums
> > > provide but that is expected/normal.
> > 
> > If library give higher value than expected by the application,
> > if the application uses this value as array index,
> > there can be an access out of bounds.
> 
> [Fiona] All asymmetric APIs are experimental so above shouldn't be a problem.
> But for the same issue with sym crypto below, I believe Ferruh's explanation makes
> sense and I don't see how there can be an API breakage.
> So if an application hasn't compiled against the new lib it will be still using the old value 
> which will be within bounds. If it's picking up the higher new value from the lib it must
> have been compiled against the lib so shouldn't have problems.

You say there is no ABI issue because the application will be re-compiled
for the updated library. Indeed, compilation fixes compatibility issues.
But this is not relevant for ABI compatibility.
ABI compatibility means we can upgrade the library without recompiling
the application and it must work.
You think it is a false positive because you assume the application
"picks" the new value. I think you miss the case where the new value
is returned by a function in the upgraded library.

> There are also no structs on the API which contain arrays using this
> for sizing, so I don't see an opportunity for an appl to have a
> mismatch in memory addresses.

Let me demonstrate where the API may "use" the new value
RTE_CRYPTO_AEAD_CHACHA20_POLY1305 and how it impacts the application.

Once upon a time a DPDK application counting the number of devices
supporting each AEAD algo (in order to find the best supported algo).
It is done in an array indexed by algo id:
	int aead_dev_count[RTE_CRYPTO_AEAD_LIST_END];
The application is compiled with DPDK 19.11,
where RTE_CRYPTO_AEAD_LIST_END = 3.
So the size of the application array aead_dev_count is 3.
This binary is run with DPDK 20.02,
where RTE_CRYPTO_AEAD_CHACHA20_POLY1305 = 3.
When calling rte_cryptodev_info_get() on a device QAT_GEN3,
rte_cryptodev_info.capabilities.sym.aead.algo is set to
RTE_CRYPTO_AEAD_CHACHA20_POLY1305 (= 3).
The application uses this value:
	++ aead_dev_count[info.capabilities.sym.aead.algo];
The application is crashing because of out of bound access.




  reply	other threads:[~2020-02-02 13:06 UTC|newest]

Thread overview: 104+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-20 15:20 [dpdk-dev] [PATCH] " David Marchand
2019-12-20 15:32 ` Richardson, Bruce
2019-12-20 16:20   ` Kinsella, Ray
2019-12-20 21:00     ` Thomas Monjalon
2020-01-06 13:17       ` Aaron Conole
2020-01-15 13:07         ` Burakov, Anatoly
2020-01-14 23:19     ` Thomas Monjalon
2020-01-15 11:33       ` Neil Horman
2020-01-15 12:38         ` Thomas Monjalon
2020-01-16 11:52           ` Neil Horman
2020-01-16 14:20             ` Thomas Monjalon
2020-01-16 18:49               ` Neil Horman
2020-01-16 20:01                 ` Thomas Monjalon
2020-01-17 19:01                   ` Neil Horman
2020-01-17 21:26                     ` David Marchand
2019-12-20 20:25 ` Neil Horman
2020-01-29 17:26 ` [dpdk-dev] [PATCH v2 0/4] " David Marchand
2020-01-29 17:26   ` [dpdk-dev] [PATCH v2 1/4] hash: fix meson headers packaging David Marchand
2020-01-30 10:12     ` Luca Boccassi
2020-01-30 10:54       ` David Marchand
2020-01-30 10:56         ` Luca Boccassi
2020-01-29 17:26   ` [dpdk-dev] [PATCH v2 2/4] build: split build helper David Marchand
2020-01-29 17:26   ` [dpdk-dev] [PATCH v2 3/4] build: test meson installation David Marchand
2020-01-29 17:26   ` [dpdk-dev] [PATCH v2 4/4] add ABI checks David Marchand
2020-01-29 17:42     ` Thomas Monjalon
2020-01-29 18:10       ` Anoob Joseph
2020-01-29 20:03         ` David Marchand
2020-01-29 20:13           ` Akhil Goyal
2020-01-30 16:09             ` Ferruh Yigit
2020-01-30 20:18               ` Thomas Monjalon
2020-01-31  9:03                 ` Ferruh Yigit
2020-01-31 10:26                   ` Ananyev, Konstantin
2020-01-31 14:16                 ` Trahe, Fiona
2020-02-02 13:05                   ` Thomas Monjalon [this message]
2020-02-02 14:41                     ` Ananyev, Konstantin
2020-02-03  9:30                       ` Ferruh Yigit
2020-02-03 11:50                         ` Neil Horman
2020-02-03 13:09                           ` Ferruh Yigit
2020-02-03 14:00                             ` Dodji Seketeli
2020-02-03 14:46                               ` Ferruh Yigit
2020-02-03 15:08                             ` Trahe, Fiona
2020-02-03 17:09                         ` Thomas Monjalon
2020-02-03 17:34                           ` Thomas Monjalon
2020-02-03 18:55                             ` Ray Kinsella
2020-02-03 21:07                               ` Thomas Monjalon
2020-02-04  9:46                                 ` Ferruh Yigit
2020-02-04 10:24                                 ` Thomas Monjalon
2020-02-04 12:44                                   ` Trahe, Fiona
2020-02-04 15:52                                     ` Trahe, Fiona
2020-02-04 15:59                                       ` Thomas Monjalon
2020-02-04 17:46                                         ` Trahe, Fiona
2020-02-13 14:51                                           ` Kusztal, ArkadiuszX
2020-03-16 12:57                                             ` Trahe, Fiona
2020-03-16 13:09                                               ` Thomas Monjalon
2020-03-17 13:27                                                 ` Kusztal, ArkadiuszX
2020-03-17 15:10                                                   ` Thomas Monjalon
2020-03-17 19:10                                                     ` Kusztal, ArkadiuszX
2020-02-04 12:57                                   ` Kevin Traynor
2020-02-04 14:44                                   ` Aaron Conole
2020-02-04 19:49                                     ` Neil Horman
2020-02-04  9:51                               ` David Marchand
2020-02-04 10:10                                 ` Trahe, Fiona
2020-02-04 10:38                                   ` Thomas Monjalon
2020-02-05 11:10                                 ` Ray Kinsella
2020-02-03 17:40                           ` Ferruh Yigit
2020-02-03 18:40                             ` Thomas Monjalon
2020-02-04  9:19                               ` Ferruh Yigit
2020-02-04  9:45                                 ` Thomas Monjalon
2020-02-04  9:56                                   ` Ferruh Yigit
2020-02-04 10:08                                     ` Bruce Richardson
2020-02-04 10:17                                     ` Kevin Traynor
2020-02-04 10:16                             ` Akhil Goyal
2020-02-04 10:28                               ` Thomas Monjalon
2020-02-04 10:32                                 ` Akhil Goyal
2020-02-04 11:35                                   ` Bruce Richardson
2020-02-04 22:10                                   ` Neil Horman
2020-02-05  6:16                                     ` [dpdk-dev] [EXT] " Anoob Joseph
2020-02-05 14:33                                       ` Trahe, Fiona
2020-02-04 21:59                               ` [dpdk-dev] " Neil Horman
2020-01-30 13:06         ` Trahe, Fiona
2020-01-30 15:59           ` Thomas Monjalon
2020-01-30 16:42             ` Ferruh Yigit
2020-01-30 23:49             ` Ananyev, Konstantin
2020-01-31  9:07               ` Ferruh Yigit
2020-01-31  9:37                 ` Ananyev, Konstantin
2020-01-30 10:57   ` [dpdk-dev] [PATCH v2 0/4] " Luca Boccassi
2020-01-30 16:00 ` [dpdk-dev] [PATCH v3 " David Marchand
2020-01-30 16:00   ` [dpdk-dev] [PATCH v3 1/4] hash: fix meson headers packaging David Marchand
2020-01-30 18:01     ` Wang, Yipeng1
2020-01-30 18:40       ` Honnappa Nagarahalli
2020-02-05 19:51         ` Wang, Yipeng1
2020-01-30 16:00   ` [dpdk-dev] [PATCH v3 2/4] build: split build helper David Marchand
2020-01-30 16:00   ` [dpdk-dev] [PATCH v3 3/4] build: test meson installation David Marchand
2020-01-30 22:17     ` Thomas Monjalon
2020-01-30 16:00   ` [dpdk-dev] [PATCH v3 4/4] add ABI checks David Marchand
2020-01-30 22:32     ` Thomas Monjalon
2020-02-01 15:29       ` David Marchand
2020-01-30 22:44     ` Thomas Monjalon
2020-02-02 21:08 ` [dpdk-dev] [PATCH v4 0/3] " David Marchand
2020-02-02 21:08   ` [dpdk-dev] [PATCH v4 1/3] hash: fix meson headers packaging David Marchand
2020-02-05 19:53     ` Wang, Yipeng1
2020-02-02 21:08   ` [dpdk-dev] [PATCH v4 2/3] build: split build helper David Marchand
2020-02-02 21:08   ` [dpdk-dev] [PATCH v4 3/3] add ABI checks David Marchand
2020-02-05 14:13   ` [dpdk-dev] [PATCH v4 0/3] " Thomas Monjalon

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