2009/11/10 Bryan Donlan <[email protected]>: > On Mon, Nov 9, 2009 at 5:47 PM, Andrew Morton <[email protected]> > wrote: > >> What happens if userspace unmaps the memory after telling the kernel to >> use it? >> >> Will processes which try to read the command line get an error reading >> /proc? If so, do all the commandline-reading programs in the world >> handle this in an appropriate fashion? > > This case can already occur in the current code; the userspace process > would have to munmap() the top of its stack, but it certainly can do > so if it tries. In any case, access_process_vm() then returns 0 > because of the fault, and thus /proc/pid/cmdline is seen to have zero > length. Since a zero-length /proc/pid/cmdline occurs with kernel > threads as well, we know this isn't a problem.
Plus, ps can read under exiting process. In this case, task->mm is NULL and proc_pid_cmdline return 0. procps tools are already NUL safe since long time ago. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
