Hello, On Dec 6, 2007 11:48 AM, Sandeep K Sinha <sandeepksinha@xxxxxxxxx> wrote: > Well, I am trying to write a kernel module which when inserted should > created a file foo at any absolute location. > This is a code snippet of the same. It returns with error No -14. > This a part of the constructor code for the module. I am using 2.6.20 kernel. > > char x1[64]="/home/ssinha/foo"; > printk(KERN_INFO "Hello world \n"); > return1 = sys_open(x1,O_CREAT | O_WRONLY | O_TRUNC,0); > printk(KERN_ALERT "Returned Value is : %d. \n",return1); > > Am I logically wrong somewhere ?? > > Regards, > Sandeep. First, I would recommend looking up the error description for the error code 14. This can be found in include/asm-generic/errno-base.h and turns out to be EFAULT "Bad address". So presumably you passed a "bad address" into the function. As far as I can see, the only address you pass is the filename. I would now recommend to look up the definition of the function sys_open(). This can be found in fs/open.c around line 1066. There the filename parameter is qualified with __user, meaning it expects an address that comes from userspace, not the kernel space. And why will this function fail if you provide it with a kernel address? It's rather simple; the kernel must not allow userspace to pass kernel addresses in its system calls, otherwise the user processes could access (read or write) kernel data! I hope this helps. Kind regards, Vegard Nossum -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
