Input: uinput - reject requests with unreasonable number of slots

Summary

In the Linux kernel, the following vulnerability has been resolved: Input: uinput - reject requests with unreasonable number of slots When exercising uinput interface syzkaller may try setting up device with a really large number of slots, which causes memory allocation failure in input_mt_init_slots(). While this allocation failure is handled properly and request is rejected, it results in syzkaller reports. Additionally, such request may put undue burden on the system which will try to free a lot of memory for a bogus request. Fix it by limiting allowed number of slots to 100. This can easily be extended if we see devices that can track more than 100 contacts.