Re: [PATCH] scsi: integer overflow in megadev_ioctl()

[Yu Chen]

I agree that the simpler fix is to change the type of 'adapno' to u32,
which is the type of uioc.adapno to u32.


2013/12/14 Måns Rullgård <mans@xxxxxxxxx>:
> "Chen.Yu" <chyyuu@xxxxxxxxx> writes:
>
>> From: "Chen.Yu" <chyyuu@xxxxxxxxx>
>>
>> There is a potential integer overflow in megadev_ioctl() if
>> userspace passes in a large u32 variable uioc.adapno.
>> The int variable adapno would < 0, leading to an error
>> array access for hdb_soft_state[adapno], or an error
>> copy_to_user(uioc.uioc_uaddr, mcontroller+adapno,..)
>>
>> Reported-by: Wenliang Fan <fanwlexca@xxxxxxxxx>
>> Suggested-by: Qixue Xiao <xiaoqixue_1@xxxxxxx>
>> Signed-off-by: Yu Chen <chyyuu@xxxxxxxxx>
>> Reviewed-by: Levente Kurusa <levex@xxxxxxxxx>
>> ---
>>  drivers/scsi/megaraid.c | 15 ++++++++++++---
>>  1 file changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/scsi/megaraid.c b/drivers/scsi/megaraid.c
>> index 816db12..0b90c54 100644
>> --- a/drivers/scsi/megaraid.c
>> +++ b/drivers/scsi/megaraid.c
>> @@ -3099,7 +3099,10 @@ megadev_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
>>               /*
>>                * Which adapter
>>                */
>> -             if( (adapno = GETADAP(uioc.adapno)) >= hba_count )
>> +             adapno = GETADAP(uioc.adapno);
>> +             if( adapno < 0 )
>> +                     return (-EINVAL);
>> +             if( adapno >= hba_count )
>>                       return (-ENODEV);
>
> This relies on implementation-defined behaviour when converting an
> unsigned integer to signed integer.  A simpler and more robust fix is to
> make the local variable 'adapno' unsigned.
>
> --
> Måns Rullgård
> mans@xxxxxxxxx



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