Hi, we have this report from 4.13.1: BUG: unable to handle kernel NULL pointer dereference at 00000004 IP: call_fext_func.isra.3+0x82/0xf0 [fujitsu_laptop] *pdpt = 0000000035e79001 *pde = 0000000000000000 Oops: 0000 [#1] PREEMPT SMP Modules linked in: ppdev ipw2200(+) libipw lib80211 cfg80211 smsc_ircc2 iTCO_wdt irda iTCO_vendor_support soundcore ptp rfkill ac97_bus pps_core lpc_ich apanel input_polldev fujitsu_laptop parport_pc i2c_i801 parport joydev shpchp floppy(+) sparse_keymap pcspkr tpm_infineon video tpm button acpi_cpufreq ac battery dm_crypt algif_skcipher af_alg hid_generic usbhid sr_mod cdrom ata_generic pcmcia radeon serio_raw ata_piix i2c_algo_bit firewire_ohci firewire_core crc_itu_t drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops yenta_socket pcmcia_rsrc pcmcia_core uhci_hcd ehci_pci ehci_hcd usbcore ttm drm dm_mirror dm_region_hash dm_log dm_mod sg CPU: 0 PID: 850 Comm: systemd-backlig Not tainted 4.13.1-1-pae #1 Hardware name: FUJITSU SIEMENS CELSIUS H230/FJNB192, BIOS Version 1.14 08/30/2005 task: f39e05c0 task.stack: f39b0000 EIP: call_fext_func.isra.3+0x82/0xf0 [fujitsu_laptop] EFLAGS: 00010256 CPU: 0 EAX: f39b1df8 EBX: 00000004 ECX: f39b1df0 EDX: f7ff03cf ESI: 00000001 EDI: f39b1e50 EBP: f39b1e5c ESP: f39b1de8 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 CR0: 80050033 CR2: 00000004 CR3: 33964e40 CR4: 000006f0 Call Trace: ? bl_update_status+0x33/0x50 [fujitsu_laptop] ? backlight_device_set_brightness+0x4b/0xb0 ? brightness_store+0x29/0x40 ? backlight_device_set_brightness+0xb0/0xb0 ? dev_attr_store+0x18/0x30 ? sysfs_kf_write+0x2e/0x50 ? sysfs_kf_bin_read+0xc0/0xc0 ? kernfs_fop_write+0xea/0x170 ? kernfs_vma_page_mkwrite+0x70/0x70 ? __vfs_write+0x22/0x150 ? common_file_perm+0x4d/0x120 ? __alloc_fd+0x9d/0x160 ? security_file_permission+0x31/0xb0 ? vfs_write+0x94/0x1a0 ? SyS_write+0x3c/0x90 ? do_fast_syscall_32+0x71/0x150 ? entry_SYSENTER_32+0x4e/0x7c Code: d0 c1 f8 1f c7 45 e0 01 00 00 00 89 45 d4 8b 45 0c c7 45 94 04 00 00 00 89 45 e4 c1 f8 1f 89 45 e8 8d 45 a4 89 45 98 8d 45 9c 50 <8b> 03 e8 e7 f4 e3 cd 85 c0 5a 75 3e f6 05 c2 23 ff f7 04 8b 45 EIP: call_fext_func.isra.3+0x82/0xf0 [fujitsu_laptop] SS:ESP: 0068:f39b1de8 CR2: 0000000000000004 ---[ end trace c655aaa8d9ba8d30 ]--- It looks like fext is NULL, but bl_update_status passes it down to call_fext_func which obviously blows up. This was originally reported here: https://bugzilla.suse.com/show_bug.cgi?id=1058814 Any ideas? thanks, -- js suse labs
