On Fri, 01 Aug 2003 12:56:01 -0700, Troy Davis wrote: > Hello- > I'm wondering if the following sequence of events is legal in a kernel > module, and if not, why. > > Get our base pointer. > Use get_free_page() to get the kernel addresses of 2 pages of memory. One > is used as a place-holder, the other as a holder for a pattern. > Set the pattern. > Disable interrupts (spin_lock_irqsave). > Copy a page of memory to one of the pages acquired above. An arbitrary page > aligned kernel address is used (not the kernel, not the base pointer page, > and not one of the pages acquired above). > Copy a pattern into the arbitrary page-aligned kernel address. > Compare the arbitrary page-aligned kernel address to the pattern. > Restore the arbitrary page-aligned kernel address. > Enable interrupts (spin_lock_irqrestore). > > My question is with interrupts disabled, the overwriting of a piece of > memory not owned by us shouldn't matter as long as it is restored before > re-enabling interrupts, or are there memory management or kernel events that > I don't know of that will make this impossible? So basically you want to overwrite some arbitrary memory and then restore it to its original value? On SMP your kernel will die a horrible death. Wes Felter - wesley@felter.org - http://felter.org/wesley/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
