Re: Kernel panic (NULL ptr deref?) in find_ge_pid()/next_pidmap()(via sys_getdents or sys_readdir)
From: Kees Cook
Date: Mon Apr 18 2011 - 15:37:55 EST
Hi Robert,
On Mon, Apr 18, 2011 at 02:57:55PM +0200, Robert ÅwiÄcki wrote:
> and a repro - should be quite obvious for FS folks, I guess
> filp->f_pos needs better checking in proc's readdir (or in llseek).
Yup:
int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
...
for (; nr < ARRAY_SIZE(proc_base_stuff); filp->f_pos++, nr++) {
...
}
ns = filp->f_dentry->d_sb->s_fs_info;
iter.task = NULL;
iter.tgid = filp->f_pos - TGID_OFFSET;
...
There's no test to validate f_pos. If it's out of bounds, the "for"
just doesn't run.
-Kees
--
Kees Cook
Ubuntu Security Team
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/