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From: "Mrozowicz, SlawomirX" <slawomirx.mrozowicz@intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>, "Doherty, Declan"
<declan.doherty@intel.com>
CC: "dev@dpdk.org" <dev@dpdk.org>, "De Lara Guarch, Pablo"
<pablo.de.lara.guarch@intel.com>
Thread-Topic: bugs and glitches in rte_cryptodev_devices_get
Thread-Index: AQHSfKvNzGDS4PCdLEmABsE9qVpYEaFXNwbg
Date: Fri, 3 Feb 2017 12:26:23 +0000
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Subject: Re: [dpdk-dev] bugs and glitches in rte_cryptodev_devices_get
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>-----Original Message-----
>From: Stephen Hemminger [mailto:stephen@networkplumber.org]
>Sent: Wednesday, February 1, 2017 5:54 PM
>To: Mrozowicz, SlawomirX <slawomirx.mrozowicz@intel.com>; Doherty,
>Declan <declan.doherty@intel.com>
>Cc: dev@dpdk.org
>Subject: bugs and glitches in rte_cryptodev_devices_get
>
>The function rte_cryptodev_devices_get has several issues. I was just goin=
g
>to fix it, but think it need to be explained.
>
>One potentially serious one (reported by coverity) is:
>
>*** CID 141067: (BAD_COMPARE)
>/lib/librte_cryptodev/rte_cryptodev.c: 503 in rte_cryptodev_devices_get()
>497 && (*devs + i)->attached =3D=3D
>498 RTE_CRYPTODEV_ATTACHED)
>{
>499
>500 dev =3D (*devs + i)->device;
>501
>502 if (dev)
>>>> CID 141067: (BAD_COMPARE)
>>>> Truncating the result of "strncmp" to "unsigned char" may cause it=
to be
>misinterpreted as 0. Note that "strncmp" may return an integer besides -1,=
0,
>or 1.
>503 cmp =3D strncmp(dev->driver->name,
>504 dev_name,
>505 strlen(dev_name));
>506 else
>507 cmp =3D strncmp((*devs + i)->data->name,
>508 dev_name,
>/lib/librte_cryptodev/rte_cryptodev.c: 507 in rte_cryptodev_devices_get()
>501
>502 if (dev)
>503 cmp =3D strncmp(dev->driver->name,
>504 dev_name,
>505 strlen(dev_name));
>506 else
>>>> CID 141067: (BAD_COMPARE)
>>>> Truncating the result of "strncmp" to "unsigned char" may cause it=
to be
>misinterpreted as 0. Note that "strncmp" may return an integer besides -1,=
0,
>or 1.
>507 cmp =3D strncmp((*devs + i)->data->name,
>508 dev_name,
>509 strlen(dev_name));
>510
>511 if (cmp =3D=3D 0)
>512 devices[count++] =3D (*devs + i)->data->dev_id;
>
>
>But also:
>
>1. Incorrect function signature:
> * function returns int but never a negative value. should be unsigned.
> * devices argument is not modified should be const.
>
>2. Original ABI seems short sighted with limit of 256 cryptodevs
> * this seems like 8 bit mindset, should really use unsigned int inste=
ad
> of uint8_t for number of devices.
>
>3. Wacky indention of the if statement.
>
>4. Make variables local to the block they are used (cmp, dev)
>
>5. Use array instead of pointer:
> ie. instead of *devs + i use devs[i]
>
We reconsider your suggestions and we addressed all your changes except add=
the const of the devices argument, since in our opinion it is not necessar=
y.
>
>The overall code in question is:
>
>
>int
>rte_cryptodev_devices_get(const char *dev_name, uint8_t *devices,
> uint8_t nb_devices)
>{
> uint8_t i, cmp, count =3D 0;
> struct rte_cryptodev **devs =3D &rte_cryptodev_globals->devs;
> struct rte_device *dev;
>
> for (i =3D 0; i < rte_cryptodev_globals->max_devs && count <
>nb_devices;
> i++) {
>
> if ((*devs + i)
> && (*devs + i)->attached =3D=3D
> RTE_CRYPTODEV_ATTACHED)
>{
>
> dev =3D (*devs + i)->device;
>
> if (dev)
> cmp =3D strncmp(dev->driver->name,
> dev_name,
> strlen(dev_name));
> else
> cmp =3D strncmp((*devs + i)->data->name,
> dev_name,
> strlen(dev_name));
>
> if (cmp =3D=3D 0)
> devices[count++] =3D (*devs + i)->data->dev_id;
> }
> }
>
> return count;
>}
>
>Please fix it.
>