Re: [PATCH] linux-user: Check lock_user result for ip_mreq_source sockopts

[Laurent Vivier]

Le 09/08/2021 à 17:54, Peter Maydell a écrit :
> In do_setsockopt(), the code path for the options which take a struct
> ip_mreq_source (IP_BLOCK_SOURCE, IP_UNBLOCK_SOURCE,
> IP_ADD_SOURCE_MEMBERSHIP and IP_DROP_SOURCE_MEMBERSHIP) fails to
> check the return value from lock_user().  Handle this in the usual
> way by returning -TARGET_EFAULT.
> 
> (In practice this was probably harmless because we'd pass a NULL
> pointer to setsockopt() and the kernel would then return EFAULT.)
> 
> Fixes: Coverity CID 1459987
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> Compile-tested only; I don't have a test case to hand that
> uses these socket options.
> 
>  linux-user/syscall.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index ccd3892b2df..d2b062ea5a9 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -2121,6 +2121,9 @@ static abi_long do_setsockopt(int sockfd, int level, 
> int optname,
>                  return -TARGET_EINVAL;
>  
>              ip_mreq_source = lock_user(VERIFY_READ, optval_addr, optlen, 1);
> +            if (!ip_mreq_source) {
> +                return -TARGET_EFAULT;
> +            }
>              ret = get_errno(setsockopt(sockfd, level, optname, 
> ip_mreq_source, optlen));
>              unlock_user (ip_mreq_source, optval_addr, 0);
>              break;
> 

Applied to my linux-user-for-6.2 branch.

Thanks,
Laurent