9p/net: fix possible memory leak in p9_check_errors()

9p/net: fix possible memory leak in p9_check_errors()

When p9pdu_readf() is called with "s?d" attribute, it allocates a pointer
that will store a string. But when p9pdu_readf() fails while handling "d"
then this pointer will not be freed in p9_check_errors().

Fixes: 51a87c552dfd ("9p: rework client code to use new protocol support functions")
Reviewed-by: Christian Schoenebeck <[email protected]>
Signed-off-by: Hangyu Hua <[email protected]>
Message-ID: <20231027030302[email protected]>
Signed-off-by: Dominique Martinet <[email protected]>