The echo_interval is not limited in any way during mounting,
which makes it possible to write a large number to it. This can
cause an overflow when multiplying ctx->echo_interval by HZ in
match_server().
Add constraints for echo_interval to smb3_fs_context_parse_param().
Found by Linux Verification Center (linuxtesting.org) with Svace.
Fixes: adfeb3e00e8e1 ("cifs: Make echo interval tunable") Cc: stable@vger.kernel.org Signed-off-by: Roman Smirnov <r.smirnov@omp.ru> Signed-off-by: Steve French <stfrench@microsoft.com>