Re: [KJ] [patch] potential data-corruption fix in md.c

[Jaco Kroon <jaco@kroon.co.za>]

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Alexey Dobriyan wrote:
> On Fri, Dec 02, 2005 at 06:38:53PM +0100, Jesper Juhl wrote:
> 
>>On 12/2/05, Jaco Kroon <jaco@kroon.co.za> wrote:
>>
>>>Fix a check whereby a negative personality number passed to either
>>>register_md_personality or unregister_md_personality could potentially
>>>cause data corruption.
> 
> 
>>>--- linux-2.6.14/drivers/md/md.c.orig
>>>+++ linux-2.6.14/drivers/md/md.c
>>>@@ -3425,7 +3425,7 @@
>>>
>>> int register_md_personality(int pnum, mdk_personality_t *p)
>>> {
>>>-       if (pnum >= MAX_PERSONALITY) {
>>>+       if (pnum < 0 || pnum >= MAX_PERSONALITY) {
>>>                printk(KERN_ERR
>>>                       "md: tried to install personality %s as nr %d, but max is %lu\n",
>>>                       p->name, pnum, MAX_PERSONALITY-1);
>>>@@ -3446,7 +3446,7 @@
>>>
>>> int unregister_md_personality(int pnum)
>>> {
>>>-       if (pnum >= MAX_PERSONALITY)
>>>+       if (pnum < 0 || pnum >= MAX_PERSONALITY)
>>>                return -EINVAL;
>>>
>>
>>MAX_PERSONALITY that pnum is compared to is defined as
>>
>>#define MAX_PERSONALITY   11UL
>>
>>so might it make more sense to just switch pnum to be an "unsigned
>>long" instead of adding <0 checks?
> 
> 
> It is int in other md files. So, one may want to change int to bitwised
> enum. Or add the check.

Or just cast to (unsigned int) for the check?
Perhaps that happens implicitly?
Would that be compiler dependant?
Do we care about anything but gcc?

-- 
There are only 10 kinds of people in this world,
  those that understand binary and those that don't.
http://www.kroon.co.za/

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