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

David Laight
2025-01-15T23:29:55Z

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)
> 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;
>