Re: [PATCH net] net/rose: prevent integer overflows in rose_setsockopt()

Su Hui
2025-01-16T02:05:00Z

On 2025/1/16 07:29, David Laight wrote:
> On Wed, 15 Jan 2025 08:42:20 -0800
> Nikita Zhandarovich <n.zhandarovich@fintech.ru> wrote:
>
>> In case of possible unpredictably large arguments passed to
>> rose_setsockopt() and multiplied by extra values on top of that,
>> integer overflows may occur.
>>
>> Do the safest minimum and fix these issues by checking the
>> contents of 'opt' and returning -EINVAL if they are too large. Also,
>> switch to unsigned int and remove useless check for negative 'opt'
>> in ROSE_IDLE case.
>>
>> Found by Linux Verification Center (linuxtesting.org) with static
>> analysis tool SVACE.
>>
>> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
>> ---
>> net/rose/af_rose.c | 16 ++++++++--------
>> 1 file changed, 8 insertions(+), 8 deletions(-)
>>
>> diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c
>> index 59050caab65c..72c65d938a15 100644
>> --- a/net/rose/af_rose.c
>> +++ b/net/rose/af_rose.c
>> @@ -397,15 +397,15 @@ static int rose_setsockopt(struct socket *sock, int level, int optname,
>> {
>> struct sock *sk = sock->sk;
>> struct rose_sock *rose = rose_sk(sk);
>> - int opt;
>> + unsigned int opt;
>>
>> if (level != SOL_ROSE)
>> return -ENOPROTOOPT;
>>
>> - if (optlen < sizeof(int))
>> + if (optlen < sizeof(unsigned int))
>> return -EINVAL;
>>
>> - if (copy_from_sockptr(&opt, optval, sizeof(int)))
>> + if (copy_from_sockptr(&opt, optval, sizeof(unsigned int)))
> Shouldn't all those be 'sizeof (opt)' ?
>
> David
>
>> return -EFAULT;
>>
>> switch (optname) {
>> @@ -414,31 +414,31 @@ static int rose_setsockopt(struct socket *sock, int level, int optname,
>> return 0;
>>
>> case ROSE_T1:
>> - if (opt < 1)
>> + if (opt < 1 || opt > UINT_MAX / HZ)

'rose->t1' is unsigned long, how about 'opt > ULONG_MAX / HZ' ?

BTW, I think only in 32bit or 16bit machine when 'sizeof(int) ==
sizeof(unsigned long)',
this integer overflows may occur..

Su Hui

>> return -EINVAL;
>> rose->t1 = opt * HZ;
>> return 0;
>>
>> case ROSE_T2:
>> - if (opt < 1)
>> + if (opt < 1 || opt > UINT_MAX / HZ)
>> return -EINVAL;
>> rose->t2 = opt * HZ;
>> return 0;
>>
>> case ROSE_T3:
>> - if (opt < 1)
>> + if (opt < 1 || opt > UINT_MAX / HZ)
>> return -EINVAL;
>> rose->t3 = opt * HZ;
>> return 0;
>>
>> case ROSE_HOLDBACK:
>> - if (opt < 1)
>> + if (opt < 1 || opt > UINT_MAX / HZ)
>> return -EINVAL;
>> rose->hb = opt * HZ;
>> return 0;
>>
>> case ROSE_IDLE:
>> - if (opt < 0)
>> + if (opt > UINT_MAX / (60 * HZ))
>> return -EINVAL;
>> rose->idle = opt * 60 * HZ;
>> return 0;
>>