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

[David Laight <david.laight.linux@gmail.com>]

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;
>