Re: [PATCH for-6.2 1/4] net: Zero sockaddr_in in parse_host_port()

[Eric Blake]

On Fri, Aug 13, 2021 at 04:05:03PM +0100, Peter Maydell wrote:
> We don't currently zero-initialize the 'struct sockaddr_in' that
> parse_host_port() fills in, so any fields we don't explicitly
> initialize might be left as random garbage.  POSIX states that
> implementations may define extensions in sockaddr_in, and that those
> extensions must not trigger if zero-initialized.  So not zero
> initializing might result in inadvertently triggering an impdef
> extension.
> 
> memset() the sockaddr_in before we start to fill it in.

Technically, POSIX recommends default initialization, as in:

struct sockaddr_in sa = { 0 };
or:
static struct sockaddr_in sa_init;
struct sockaddr_in sa = sa_init;

because of odd platforms where default initialization compiles to
non-zero bits (think platforms where NULL and/or floating point 0.0 do
not have an all-zero-bit representation - yes, C is weird).  But in
practice, that does not plague any of the hardware qemu cares about,
so I'm just fine with memset.

> 
> Fixes: Coverity CID 1005338
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  net/net.c | 2 ++
>  1 file changed, 2 insertions(+)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
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