2020-08-03 12:54:06

by Herbert Xu

Subject: Re: [PATCH] crypto: ccp - zero the cmd data after use it

On Mon, Aug 03, 2020 at 03:58:58PM +0800, Liwei Song wrote:
> exist the following assignment in ccp(ignore the force
> convert of the struct) by list_del in ccp_dequeue_cmd():
> req->__ctx->cmd->entry->next = LIST_POISON1;
>
> after use the req, kzfree(req) can not zero the entry
> entry->next = LIST_POISON1 of the ccp_cmd(cmd) struct
> when this address available as slub freelist pointer, this will cause
> the following "general protection fault" error if some process meet
> this LIST_POISON1 value address when request memory:

Your description makes no sense. Please rewrite it and explain
the problem properly.

Thanks,
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

2020-08-04 03:52:32

by Liwei Song

Subject: Re: [PATCH] crypto: ccp - zero the cmd data after use it

On 8/3/20 20:52, Herbert Xu wrote:
> On Mon, Aug 03, 2020 at 03:58:58PM +0800, Liwei Song wrote:
>> exist the following assignment in ccp(ignore the force
>> convert of the struct) by list_del in ccp_dequeue_cmd():
>> req->__ctx->cmd->entry->next = LIST_POISON1;
>>
>> after use the req, kzfree(req) can not zero the entry
>> entry->next = LIST_POISON1 of the ccp_cmd(cmd) struct
>> when this address available as slub freelist pointer, this will cause
>> the following "general protection fault" error if some process meet
>> this LIST_POISON1 value address when request memory:
>
> Your description makes no sense. Please rewrite it and explain
> the problem properly.

The problem here is that the entry of struct ccp_cmd is not zeroed after we use it,
If the other process got this address by kmalloc(), this illegal value "LIST_POISON1"
will cause "general protection fault" error.

Thanks,
Liwei.


>
> Thanks,
>