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Re: [Qemu-devel] [PATCH for-2.9] sockets: Fix socket_address_to_string()
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH for-2.9] sockets: Fix socket_address_to_string() hostname truncation |
Date: |
Thu, 23 Mar 2017 12:40:24 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 |
On 23/03/2017 12:23, Markus Armbruster wrote:
> We first snprintf() to a fixed buffer, then g_strdup() the result
> *boggle*.
>
> Worse, the size of the fixed buffer INET6_ADDRSTRLEN + 5 + 4 is bogus:
> the 4 correctly accounts for '[', ']', ':' and '\0', but
> INET6_ADDRSTRLEN is not a suitable limit for inet->host, and 5 is not
> one for inet->port! They are for host and port in *numeric* form
> (exploiting that INET6_ADDRSTRLEN > INET_ADDRSTRLEN), but inet->host
> can also be a hostname, and inet->port can be a service name, to be
> resolved with getaddrinfo().
>
> Fortunately, the only user so far is the "socket" network backend's
> net_socket_connected(), which uses it to initialize a NetSocketState's
> info_str[]. info_str[] has considerable more space: 256 instead of
> 55. So the bug's impact appears to be limited to truncated "info
> networks" with the "socket" network backend.
>
> The fix is obvious: use g_strdup_printf().
>
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
> util/qemu-sockets.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
> index 7c120c4..40164bf 100644
> --- a/util/qemu-sockets.c
> +++ b/util/qemu-sockets.c
> @@ -1307,19 +1307,14 @@ char *socket_address_to_string(struct SocketAddress
> *addr, Error **errp)
> {
> char *buf;
> InetSocketAddress *inet;
> - char host_port[INET6_ADDRSTRLEN + 5 + 4];
/me learnt about INET6_ADDRSTRLEN today.
> switch (addr->type) {
> case SOCKET_ADDRESS_KIND_INET:
> inet = addr->u.inet.data;
> if (strchr(inet->host, ':') == NULL) {
> - snprintf(host_port, sizeof(host_port), "%s:%s", inet->host,
> - inet->port);
> - buf = g_strdup(host_port);
> + buf = g_strdup_printf("%s:%s", inet->host, inet->port);
> } else {
> - snprintf(host_port, sizeof(host_port), "[%s]:%s", inet->host,
> - inet->port);
> - buf = g_strdup(host_port);
> + buf = g_strdup_printf("[%s]:%s", inet->host, inet->port);
> }
> break;
>
>
Reviewed-by: Paolo Bonzini <address@hidden>