hi jeremy, i'm not sure if this will fix your problem, but the iname array is declared to hold only 4 chars and the strcpy will copy 5 chars into it, potentially overwriting something important. the 5th char is the null byte. > > strcpy(iname, "eth0"); > peace, dan > -----Original Message----- > From: Jeremy Andrus [mailto:jandru39@calvin.edu] > Sent: Friday, August 02, 2002 4:50 PM > To: Kernelnewbies > Cc: clug@calvin.edu > Subject: IP address in the kernel > > > OK. I've written some code based on Trevor Hamm's suggestions, but it > segfaults. Here's what I have: > > ----- BEGIN CODE ----- > struct in_device *in_dev; > struct in_ifaddr **ifap = NULL; > struct in_ifaddr *ifa = NULL; > struct net_device *dev; > struct in_addr in; > unsigned long pci_ip_dword; > char iname[4]; > > strcpy(iname, "eth0"); > if ( (dev = dev_get_by_name(iname)) == NULL ) { > printk(" |--> Couldn't find a network interface.\n"); > printk(" You need at least one interface (eth0) for this > netfilter hook to work.\n"); > return 0; > } > printk("Looking for 'eth0' . . .\n"); > if ( (in_dev = in_dev_get(dev)) != NULL ) { > if (ifa == NULL) { > for (ifap=&in_dev->ifa_list; (ifa=*ifap) != NULL; > ifap=&ifa->ifa_next) > if (strcmp(iname, ifa->ifa_label) == 0) > break; > } > } > > printk("making dword . . .\n"); > in.s_addr = ifa->ifa_local; > pci_ip_dword = (unsigned long)in.s_addr; > pci_ip_dword = (pci_ip_dword << 15); > pci_ip_dword = (pci_ip_dword & 0x7F800000); > printk("My IP address dword is: %lx\n", (unsigned > long)pci_ip_dword); > > ----- END CODE ----- > > When I modprobe my netfilter target, dmesg has this in it: > > ----- BEGIN DMESG DUMP ----- > Looking for 'eth0' . . . > making dword . . . > My IP address dword is: 54000000 > making a note of it . . . > Unable to handle kernel NULL pointer dereference at virtual address > 00000011 > printing eip: > e0840a02 > *pde = 00000000 > Oops: 0002 > CPU: 0 > EIP: 0010:[<e0840a02>] Not tainted > EFLAGS: 00010286 > eax: 00000001 ebx: e08480b0 ecx: 30687465 edx: 00000001 > esi: 00000070 edi: e0848040 ebp: 00000000 esp: def73d74 > ds: 0018 es: 0018 ss: 0018 > Process iptables (pid: 102, stackpage=def73000) > Stack: def73e08 e0848040 e08480d0 00000000 00000002 00000000 00000163 > e084a040 > 00000000 def73dc0 e084b000 c0126c4f def73dc0 00000000 e084833c > e0848040 > 00000000 0004b000 00000000 00000000 e0841149 def73e08 0000000e > e0848000 > Call Trace: [<c0126c4f>] [<e0841149>] [<e084161b>] [<e0842880>] > [<c01bf540>] > [<c01bf5a2>] [<c01cabef>] [<c010ff03>] [<c01e0318>] [<c01e5c7a>] > [<c01b42f1>] > [<c01b4996>] [<c0106c5b>] > > Code: ff 40 10 8b 42 34 80 48 14 18 89 53 04 b9 80 27 84 e0 ff 05 > > ----- END DMESG DUMP ----- > > The pci_ip_dword isn't correct either. Grrrr. Kernel hacking. Grrrr. > > -Jeremy > > > -- > ---------------------------- > Jeremy C. Andrus > http://www.jeremya.com/ > ---------------------------- > -- > Kernelnewbies: Help each other learn about the Linux kernel. > Archive: http://mail.nl.linux.org/kernelnewbies/ > FAQ: http://kernelnewbies.org/faq/ > > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
