Re: [PATCH] Do not segfault because of kernel version

[Luk Claes <luk@debian.org>]

On 07/03/2011 07:04 AM, NeilBrown wrote:
> On Sat,  2 Jul 2011 16:32:29 +0200 Luk Claes <luk@debian.org> wrote:
> 
>> mount.nfs segfaults if kernel version number does not contain
>> at least 3 components delimited with a dot.
>>
>> Avoid this by matching up to three unsigned integers inialised
>> to zero, separated by dots.
>>
>> Signed-off-by: Luk Claes <luk@debian.org>
>> ---
>>  utils/mount/version.h |   11 +++++------
>>  1 files changed, 5 insertions(+), 6 deletions(-)
>>
>> diff --git a/utils/mount/version.h b/utils/mount/version.h
>> index af61a6f..2642eab 100644
>> --- a/utils/mount/version.h
>> +++ b/utils/mount/version.h
>> @@ -23,8 +23,7 @@
>>  #ifndef _NFS_UTILS_MOUNT_VERSION_H
>>  #define _NFS_UTILS_MOUNT_VERSION_H
>>  
>> -#include <stdlib.h>
>> -#include <string.h>
>> +#include <stdio.h>
>>  
>>  #include <sys/utsname.h>
>>  
>> @@ -37,14 +36,14 @@ static inline unsigned int MAKE_VERSION(unsigned int p, unsigned int q,
>>  static inline unsigned int linux_version_code(void)
>>  {
>>  	struct utsname my_utsname;
>> -	unsigned int p, q, r;
>> +	unsigned int p, q = 0, r = 0;
>>  
>>  	if (uname(&my_utsname))
>>  		return 0;
>>  
>> -	p = (unsigned int)atoi(strtok(my_utsname.release, "."));
>> -	q = (unsigned int)atoi(strtok(NULL, "."));
>> -	r = (unsigned int)atoi(strtok(NULL, "."));
>> +	if (sscanf(my_utsname.release, "%u.%u.%u", &p, &q, &r) < 1)
>> +		return 0;
>> +	
> 
> According to Linus, the error case should return a big number, not a small
> number.
> So if the version number is not recognised - e.g. it was written in Sanskrit
> rather than arabic numberals, it is assumed to be a future version, not a
> past version.
> 
>  https://lkml.org/lkml/2011/6/14/293

Ah, not a bad idea. In that case a parse error can be distinguished from
other errors. Would 'return -1' do the expected or will it give a
compiler warning/error we should avoid?

Cheers

Luk