Re: 2.6.0-mm1 - kernel panic (VFS bug?)

[Nick Piggin <piggin@cyberone.com.au>]

Libor Vanek wrote:

> Hi,
> I'm trying to do some debugging with 2.6.0 + mm1 patch (I attach my 
> .config) and I found out this very strange thing when changing 
> fs/open.c (about the line 933):
>
> ORIGINAL CODE:
> ...
> asmlinkage long sys_open(const char __user * filename, int flags, int 
> mode)
> {
>        char * tmp;
>        int fd, error;
>
> #if BITS_PER_LONG != 32
>        flags |= O_LARGEFILE;
> #endif
>        tmp = getname(filename);
>        fd = PTR_ERR(tmp);
> ...
>
>
> MY TINY MODIFICATION:
> ...
> asmlinkage long sys_open(const char __user * filename, int flags, int 
> mode)
> {
>        char * tmp;
>        int fd, error;
>     char tmp_path[PATH_MAX],tmp2_path[PATH_MAX];
>
>
> #if BITS_PER_LONG != 32
>        flags |= O_LARGEFILE;
> #endif
>        tmp = getname(filename);
>     printk (KERN_INFO "sys_open: %s\n",tmp);
>        fd = PTR_ERR(tmp);
> ...
>
>
> This causes kernel to panic during boot. Messages are: (maybe some 
> typos - writing from paper)
> ...
> NET: Registering protocol family 17
> Unable to handle kernel paging request at virtual address fffffff2 


getname can return errors, actually. Looks like you're trying to print
the string at address -EFAULT.

When in doubt, always suspect your code.