Le 28/03/2021 à 20:01, Frédéric Fortier via a écrit :
> getsockopt(fd, SOL_NETLINK, NETLINK_LIST_MEMBERSHIPS, *optval, *optlen)
> syscall allows optval to be NULL/invalid if optlen points to a size of
> zero. This allows userspace to query the length of the array they should
> use to get the full membership list before allocating memory for said
> list, then re-calling getsockopt with proper optval/optlen arguments.
>
> Notable users of this pattern include systemd-networkd, which in the
> (albeit old) version 237 tested, cannot start without this fix.
>
> Signed-off-by: Frédéric Fortier <f...@ghgsat.com>
> ---
> linux-user/syscall.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 1e508576c7..9b7556a9a2 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -3025,7 +3025,7 @@ get_timeout:
> return -TARGET_EINVAL;
> }
> results = lock_user(VERIFY_WRITE, optval_addr, len, 1);
> - if (!results) {
> + if (!results && len > 0) {
> return -TARGET_EFAULT;
> }
> lv = len;
>
Reviewed-by: Laurent Vivier <laur...@vivier.eu>
