我已经编写了这个简单的模块来处理设备并调用它的一些电源管理方法，例如.suspend和.resume。在初始化时，模块简单地查找特定设备并尝试调用其方法。
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/pci.h>
static int __init mfps_driver_init(void){
struct pci_dev *dev = NULL;
struct pci_driver *driver = NULL;
struct device *device = NULL;
dev = pci_get_device(0x8086, 0x15a2, NULL);
if((dev == NULL) || (dev == 0)){
printk(KERN_INFO "LEONZO: NOTHING FOUND SIZE %ld\n", sizeof(dev));
} else {
driver = dev->driver;
printk(KERN_INFO "LEONZO: I FOUND THE DEVICE OF THE SIZE %ld\n", sizeof(dev));
printk(KERN_INFO "LEONZO: HERE IS ITS DRIVER NAME %s\n", driver->name);
*device = dev->dev;
device_lock(device);
device_unlock(device);
}
return 0;
}
static void __exit mfps_driver_exit(void){
}
module_init(mfps_driver_init);
module_exit(mfps_driver_exit);
代码编译成功。但是当我加载模块时，我得到了一个内核错误：
sudo insmod MyFirstPowerState.ko
dmesg显示以下输出
[ 59.545180] MyFirstPowerState: module license 'unspecified' taints kernel.
[ 59.545183] Disabling lock debugging due to kernel taint
[ 59.546010] LEONZO: I FOUND THE DEVICE OF THE SIZE 8
[ 59.546012] LEONZO: HERE IS ITS DRIVER NAME e1000e
[ 59.546013] LEONZO: CALLING IT SUSPEND METHOD
[ 59.546021] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 59.546051] IP: [<ffffffffc011907e>] mfps_driver_init+0x7e/0x1000 [MyFirstPowerState]
[ 59.546077] PGD 0
[ 59.546085] Oops: 0002 [#1] SMP
[ 59.546097] Modules linked in: MyFirstPowerState(POE+) xt_CHECKSUM arc4 iwlmvm mac80211 snd_hda_codec_hdmi snd_hda_codec_realtek iwlwifi snd_hda_codec_generic rtsx_pci_ms memstick cfg80211 nf_conntrack_netbios_ns nf_conntrack_broadcast ipt_MASQUERADE nf_nat_masquerade_ipv4 xt_tcpudp ip6t_REJECT nf_reject_ipv6 ipt_REJECT nf_reject_ipv4 xt_conntrack ebtable_nat ebtable_broute bridge stp llc ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw iptable_filter ip_tables x_tables dm_crypt hp_wmi sparse_keymap intel_rapl iosf_mbi x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm crct10dif_pclmul dm_multipath crc32_pclmul scsi_dh aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd joydev serio_raw lpc_ich uvcvideo snd_seq_midi snd_seq_midi_event snd_rawmidi snd_hda_intel snd_hda_controller snd_hda_codec videobuf2_vmalloc snd_hwdep shpchp snd_pcm videobuf2_memops videobuf2_core v4l2_common snd_seq e1000e(OE) i915_bpo ptp mei_me pps_core mei videodev media snd_seq_device intel_ips snd_timer drm_kms_helper drm btusb snd i2c_algo_bit soundcore 8250_fintek hp_accel lis3lv02d input_polldev tpm_infineon hp_wireless mac_hid parport_pc ppdev lp parport rfcomm bnep bluetooth binfmt_misc btrfs xor raid6_pq dm_mirror dm_region_hash dm_log uas usb_storage hid_generic usbhid hid rtsx_pci_sdmmc ahci psmouse libahci rtsx_pci wmi video
[ 59.546577] CPU: 1 PID: 4180 Comm: insmod Tainted: P OE 3.19.0-51-generic #58~14.04.1-Ubuntu
[ 59.546613] Hardware name: Hewlett-Packard HP EliteBook 840 G2/2216, BIOS M71 Ver. 01.05 03/26/2015
[ 59.546648] task: ffff880241a7b110 ti: ffff880242f68000 task.ti: ffff880242f68000
[ 59.546678] RIP: 0010:[<ffffffffc011907e>] [<ffffffffc011907e>] mfps_driver_init+0x7e/0x1000 [MyFirstPowerState]
[ 59.546720] RSP: 0018:ffff880242f6bd18 EFLAGS: 00010246
[ 59.546741] RAX: 0000000000000000 RBX: ffff880245b4d000 RCX: 00000000000000ae
[ 59.546772] RDX: 0000000000000000 RSI: ffff880245b4d098 RDI: 0000000000000000
[ 59.546807] RBP: ffff880242f6bd28 R08: 000000000000000a R09: 0000000000000000
[ 59.546839] R10: 0000000000000d53 R11: ffff880242f6b9de R12: ffffffffc06a8000
[ 59.546868] R13: 0000000000000000 R14: ffffffffc0119000 R15: ffff880242f6bef8
[ 59.546900] FS: 00007f8787aa6740(0000) GS:ffff88024f440000(0000) knlGS:0000000000000000
[ 59.546921] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 59.546936] CR2: 0000000000000000 CR3: 0000000244393000 CR4: 00000000003407e0
[ 59.546955] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 59.546978] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 59.547006] Stack:
[ 59.547014] ffffffff81c1d060 ffff880204cd3280 ffff880242f6bda8 ffffffff81002144
[ 59.547046] 0000000000000001 0000000000000002 ffff8801f8ddc4c0 0000000000000001
[ 59.547079] ffff880242f6bd88 ffffffff811cef19 ffffffff810f7aac 0000000000000018
[ 59.547114] Call Trace:
[ 59.547131] [<ffffffff81002144>] do_one_initcall+0xd4/0x210
[ 59.547162] [<ffffffff811cef19>] ? kmem_cache_alloc_trace+0x199/0x220
[ 59.547194] [<ffffffff810f7aac>] ? load_module+0x164c/0x1cc0
[ 59.547222] [<ffffffff810f7ae5>] load_module+0x1685/0x1cc0
[ 59.547247] [<ffffffff810f3380>] ? store_uevent+0x40/0x40
[ 59.547274] [<ffffffff810f8296>] SyS_finit_module+0x86/0xb0
[ 59.547298] [<ffffffff817b788d>] system_call_fastpath+0x16/0x1b
[ 59.547314] Code: c7 80 c0 4b c0 31 c0 e8 19 14 69 c1 48 c7 c7 a8 c0 4b c0 31 c0 e8 0b 14 69 c1 31 c0 48 8d b3 98 00 00 00 b9 ae 00 00 00 48 89 c7 <f3> a5 bf 60 00 00 00 e8 26 c7 69 c1 bf 60 00 00 00 e8 ac c5 69
[ 59.547393] RIP [<ffffffffc011907e>] mfps_driver_init+0x7e/0x1000 [MyFirstPowerState]
[ 59.547416] RSP <ffff880242f6bd18>
[ 59.547425] CR2: 0000000000000000
[ 59.554577] ---[ end trace 42e3b1c73677cdfa ]---
我还注意到因此无法移除模块：
sudo rmmod MyFirstPowerState.ko
rmmod: ERROR: Module MyFirstPowerState is in use
知道这段代码的含义以及如何纠正错误？
答案 0 :(得分：1)
您对代码的特殊问题在于此声明：
*device = dev->dev;
设备变量初始化为NULL。您正在尝试写入此变量指向的地址，这会导致NULL指针取消引用。