svn commit: r300258 - head/sys/dev/iicbus

[Jason Harmening]

On 05/19/16 20:50, Ravi Pokala wrote:
> -----Original Message-----
> From: <owner-src-committers at freebsd.org> on behalf of "Jason A. Harmening" <jah at FreeBSD.org>
> Date: 2016-05-19, Thursday at 20:03
> To: <src-committers at freebsd.org>, <svn-src-all at freebsd.org>, <svn-src-head at freebsd.org>
> Subject: svn commit: r300258 - head/sys/dev/iicbus
> 
>> Author: jah
>> Date: Fri May 20 03:03:04 2016
>> New Revision: 300258
>> URL: https://svnweb.freebsd.org/changeset/base/300258
>>
>> Log:
>>  iic_rdwr_data->nmsgs is uint32_t, so limit the allowable number of messages to prevent memory exhaustion and short allocations on 32-bit systems. Since iicrdwr is intended to be a workalike of a Linux i2c-dev call, use the same limit of 42 that Linux uses.
>>  
>>  Also check the return value of copyin(9) to prevent unnecessary allocation in the failure case.
>>  
>>  ...
>>  
>> 	error = copyin(d->msgs, buf, sizeof(*d->msgs) * d->nmsgs);
>> +	if (error != 0) {
>> +		free(buf, M_IIC);
>> +		return (error);
>> +	}
>>
> 
> Hi Jason,
> 
> If I’m reading that right, it’s not preventing any allocations, but it is preventing a leak. Is that correct?
> 
> Thanks,
> 
> Ravi (rpokala@)
> 
> 

Hi Ravi,

There shouldn't be a leak in here, but checking the result prevents
falling through the rest of the function, including the unnecessary
malloc of usrbufs right after this.  It also makes the error handling
clearer.

Thanks,
Jason

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