On Thu, May 28, 2015 at 01:12:14AM +0300, Alexey Dobriyan wrote: > On Thu, May 28, 2015 at 01:02:29AM +0300, Cyrill Gorcunov wrote: > > On Thu, May 28, 2015 at 12:47:57AM +0300, Alexey Dobriyan wrote: > > > Individual prctl(PR_SET_MM_*) calls do some checking to maintain > > > consistent view of mm->arg_start et al fields, but not enough. > > > In particular > > > PR_SET_MM_ARG_START/PR_SET_MM_ARG_END/PR_SET_MM_ENV_START/PR_SET_MM_ENV_END > > > only check that address lies in existent VMA, but doesn't check that > > > start address is lower that end address _at all_. > > > > > > Consolidate all consistency checks, so there will be no difference in > > > the future between PR_SET_MM_MAP and individual PR_SET_MM_* calls. > > > > > > The program below makes both ARGV and ENVP areas reverted, > > > makes /proc/$PID/cmdline show garbage (doesn't oops by luck). > > > > Why should it oops? > > Anything can happen if you constantly write code like this > > unsigned long len = mm->arg_end - mm->arg_start; > > and expect result to be positive.
It won't 'cause proc code will limit it (this where 'luck' comes from :). Anyway, switching to validate() helper will make code more robust, so thank you! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
