I tried to update to linux- image-4.13.0-041300rc2-generic_4.13.0-041300rc2.201707232231_i386.deb, but I was told it was no longer possible to log in (the login screen appeared, but it was not possible to write password as if the keyboard was not connected at all). After reverting to the previous kernel it was possible to log in again.
However, I still have some findings that may be useful. I tried to add some debug printk's around the code that caused the null pointer dereference and I was able to find the exact place where the null pointer dereference occurs. I used Ubuntu-hwe-4.8.0-58.63_16.04.1 for that. The problem is in usb_ifnum_to_if where config->interface[i] is null (http://kernel.ubuntu.com/git/ubuntu/ubuntu- xenial.git/tree/drivers/usb/core/usb.c?h=Ubuntu- hwe-4.8.0-58.63_16.04.1&id=2e1f960b96b3d80fc2b91809bf0cb02c97abe8f4#n144) Here's a short snippet of the code: for (i = 0; i < config->desc.bNumInterfaces; i++) { if (config->interface[i]->altsetting[0] /* config->interface[i] == 0 here! */ .desc.bInterfaceNumber == ifnum) { return config->interface[i]; } } And it's not a single interface that fails, it seems that all interfaces are null, since the changed code that I used for debugging actually looks like this: for (i = 0; i < config->desc.bNumInterfaces; i++) { if (config->interface[i] == 0) { printk(KERN_ALERT "DEBUG: Interface %d is null\n", i); continue; } if (config->interface[i]->altsetting[0] .desc.bInterfaceNumber == ifnum) { return config->interface[i]; } } And in dmesg I found: júl 23 13:40:11 lenovo kernel: DEBUG: Interface 0 is null júl 23 13:40:12 lenovo kernel: DEBUG: Interface 1 is null júl 23 13:40:12 lenovo kernel: DEBUG: Interface 2 is null júl 23 13:40:12 lenovo kernel: DEBUG: Interface 3 is null júl 23 13:40:12 lenovo kernel: DEBUG: Interface 0 is null júl 23 13:40:13 lenovo kernel: DEBUG: Interface 1 is null júl 23 13:40:13 lenovo kernel: DEBUG: Interface 2 is null júl 23 13:40:13 lenovo kernel: DEBUG: Interface 3 is null -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1705900 Title: Lenovo e73 USB webcam problems To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1705900/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
