netlink通信的问题
写了一个netlink的内核与用户空间通信的模块，编译没有问题，但是加载模块时出现了一些错误，内核模块部分的代码如下：#include <linux/kernel.h>#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/ip.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <linux/kthread.h>
#define MAX_MSGSIZE 4096
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Koorey King");
struct sock *nl_sk = NULL;
static struct task_struct *mythread = NULL;
void sendnlmsg(char *message)
{
struct sk_buff *skb;
struct nlmsghdr *nlh;
//int len = NLMSG_SPACE(MAX_MSGSIZE);
int slen = 0;
if(!message || !nl_sk){
return;
}
skb = nlmsg_new(MAX_MSGSIZE, GFP_KERNEL);
if(!skb){
printk(KERN_ERR "my_net_link: alloc_skb Error./n");
return;
}
slen = strlen(message)+1;
nlh = nlmsg_put(skb, 0, 0, 0, MAX_MSGSIZE, 0);
NETLINK_CB(skb).portid = 0;
NETLINK_CB(skb).dst_group = 5;
message = '\0';
memcpy(NLMSG_DATA(nlh), message, slen+1);
netlink_broadcast(nl_sk, skb, 0,5, GFP_KERNEL);
printk("send OK!\n");
return;
}
static void recnldata (struct sock *sk, char *mydata)
{
struct sk_buff *skb;
struct nlmsghdr *nlh = NULL;
while((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL)
{
nlh = (struct nlmsghdr *)skb->data;
mydata = (char*)NLMSG_DATA(nlh);
printk("%s: received netlink message payload: %s \n", __FUNCTION__, mydata);
kfree_skb(skb);
}
printk("recvied finished!\n");
}
static int sending_thread(void *data)
{
int i = 10;
struct completion cmpl;
while(i--){
init_completion(&cmpl);
wait_for_completion_timeout(&cmpl, 1 * HZ);
sendnlmsg("I am from kernel!");
}
printk("sending thread exited!");
return 0;
}
static int __init myinit_module(void)
{
//struct netlink_kernel_cfg netlink_kerncfg = {
// .input = recnldata,
//};
printk("my netlink in\n");
nl_sk = netlink_kernel_create(&init_net,NETLINK_TEST,NULL);
if(!nl_sk){
printk(KERN_ERR "my_net_link: create netlink socket error.\n");
return 1;
}
printk("my netlink: create netlink socket ok.\n");
mythread = kthread_run(sending_thread,NULL,"thread_sender");
return 0;
}
static void __exit mycleanup_module(void)
{
if(nl_sk != NULL){
sock_release(nl_sk->sk_socket);
}
printk("my netlink out!\n");
}
module_init(myinit_module);
module_exit(mycleanup_module);加载模块后dmesg信息如下：
[ 5927.075021] my netlink in
[ 5927.075031] my netlink: create netlink socket ok.
[ 5928.073283] BUG: unable to handle kernel paging request at f87740c4
[ 5928.073288] IP: [<f8773076>] sendnlmsg+0x76/0x110
[ 5928.073292] *pdpt = 0000000001a45001 *pde = 0000000036a74067 *pte = 800000007dc00161
[ 5928.073295] Oops: 0003 [#6] SMP
[ 5928.073297] Modules linked in: kernelspace(OF) coretemp crc32_pclmul(F) aesni_intel(F) aes_i586(F) xts(F) lrw(F) gf128mul(F) ablk_helper(F) cryptd(F) vmw_balloon(F) snd_ens1371 snd_ac97_codec microcode(F) ac97_bus gameport(F) psmouse(F) serio_raw(F) snd_pcm(F) snd_page_alloc(F) snd_seq_midi(F) snd_seq_midi_event(F) snd_rawmidi(F) snd_seq(F) snd_seq_device(F) snd_timer(F) ppdev(F) snd(F) bnep rfcomm btusb soundcore(F) vmwgfx bluetooth ttm drm binfmt_misc(F) vmw_vmci parport_pc(F) mac_hid i2c_piix4 shpchp lp(F) parport(F) hid_generic usbhid hid vmw_pvscsi(F) ahci(F) libahci(F) pcnet32(F) mii(F) floppy(F) vmxnet3(F) mptspi(F) mptscsih(F) mptbase(F)
[ 5928.073322] CPU: 1 PID: 8406 Comm: thread_sender Tainted: GF D O 3.11.0-12-generic #19-Ubuntu
[ 5928.073324] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013
[ 5928.073325] task: f1330ce0 ti: f441a000 task.ti: f441a000
[ 5928.073327] EIP: 0060:[<f8773076>] EFLAGS: 00010282 CPU: 1
[ 5928.073328] EIP is at sendnlmsg+0x76/0x110
[ 5928.073329] EAX: ef9d2010 EBX: f1df9840 ECX: 00000012 EDX: f87740b2
[ 5928.073330] ESI: f87740b2 EDI: 00000011 EBP: f441bf4c ESP: f441bf30
[ 5928.073332]DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[ 5928.073333] CR0: 80050033 CR2: f87740c4 CR3: 32106000 CR4: 001407f0
[ 5928.073338] Stack:
[ 5928.073338]00000000 00001000 00000000 00000012 0000000a 00000000 f8773110 f441bf6c
[ 5928.073342]f8773158 c1079b58 00000000 00000202 f441bf60 f441bf60 f472ddb0 f441bfac
[ 5928.073345]c1070164 00000000 f441bf78 00000000 00000000 c1070000 f441bf88 f441bf88
[ 5928.073349] Call Trace:
[ 5928.073351][<f8773110>] ? sendnlmsg+0x110/0x110
[ 5928.073353][<f8773158>] sending_thread+0x48/0x61
[ 5928.073358][<c1079b58>] ? complete+0x48/0x50
[ 5928.073360][<c1070164>] kthread+0x94/0xa0
[ 5928.073362][<c1070000>] ? __kthread_parkme+0x60/0x70
[ 5928.073369][<c1632c37>] ret_from_kernel_thread+0x1b/0x28
[ 5928.073370][<c10700d0>] ? kthread_create_on_node+0xc0/0xc0
[ 5928.073372] Code: 51 a1 b8 c8 8b 53 54 85 d2 89 c7 8d 40 01 89 45 f0 b8 10 00 00 00 74 55 8b 4d f0 89 f2 c7 43 24 00 00 00 00 c7 43 28 05 00 00 00 <c6> 44 3e 01 00 83 c1 01 e8 0d 9d b8 c8 a1 80 51 77 f8 31 c9 89
[ 5928.073392] EIP: [<f8773076>] sendnlmsg+0x76/0x110 SS:ESP 0068:f441bf30
[ 5928.073395] CR2: 00000000f87740c4
[ 5928.073396] ---[ end trace 5903863cf1e9ba73 ]---
希望大家帮我看下是哪里的错误，感激不尽 没有反汇编，不能确认，大概看了下代码，如下代码应该有问题：
message = '\0';
这里的message应该是通过入参传入的字符串常量，该常量应该是存放在代码段中的，应该只有只读和执行权限，没有write权限，你这里直接赋值显然有问题。
另外，这里的数组也越界了：slen = strlen(message)+1;
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