Re: [PATCH 7/9] bsd-user: do_freebsd_sysctl helper for sysctl(2)

[Richard Henderson]

On 2/10/23 13:18, Warner Losh wrote:
> +abi_long do_freebsd_sysctl(CPUArchState *env, abi_ulong namep, int32_t namelen,
> +        abi_ulong oldp, abi_ulong oldlenp, abi_ulong newp, abi_ulong newlen)
> +{
> +    abi_long ret;
> +    void *hnamep, *holdp = NULL, *hnewp = NULL;
> +    size_t holdlen;
> +    abi_ulong oldlen = 0;
> +    int32_t *snamep = g_malloc(sizeof(int32_t) * namelen), *p, *q, i;
> +
> +    if (oldlenp) {
> +        if (get_user_ual(oldlen, oldlenp)) {
> +            return -TARGET_EFAULT;
> +        }
> +    }

You need to check for write early.  Either access_ok, or lock_user.

> +    for (p = hnamep, q = snamep, i = 0; i < namelen; p++, i++) {
> +        *q++ = tswap32(*p);
> +    }

Why the inconsistent increments?

> +    unlock_user(holdp, oldp, holdlen);

Usually we don't want writeback on error.


r~