Messages in this thread | | | Date | Thu, 12 Jan 2006 16:58:26 -0800 | From | Andrew Morton <> | Subject | Re: [patch 5/13] s390: show_task oops. |
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Martin Schwidefsky <schwidefsky@de.ibm.com> wrote: > > From: Heiko Carstens <heiko.carstens@de.ibm.com> > > [patch 5/13] s390: show_task oops. > > The show_task function walks the kernel stack backchain of > processes assuming that the processes are not running. Since > this assumption is not correct walking the backchain can lead > to an addressing exception and therefore to a kernel hang. > So prevent the kernel hang (you still get incorrect results) > verity that all read accesses are within the bounds of the > kernel stack before performing them. >
This one needs to be thought about and tested versus the just-merged s390-task_stack_page.patch. I guess it'll still work, but some of the pretty new accessors could be used in there, at least.
> --- linux-2.6/arch/s390/kernel/process.c 2006-01-12 15:43:19.000000000 +0100 > +++ linux-2.6-patched/arch/s390/kernel/process.c 2006-01-12 15:43:55.000000000 +0100 > @@ -58,10 +58,19 @@ asmlinkage void ret_from_fork(void) __as > */ > unsigned long thread_saved_pc(struct task_struct *tsk) > { > - struct stack_frame *sf; > + struct stack_frame *sf, *low, *high; > > - sf = (struct stack_frame *) tsk->thread.ksp; > - sf = (struct stack_frame *) sf->back_chain; > + if (!tsk || !tsk->thread_info) > + return 0; > + low = (struct stack_frame *) tsk->thread_info; > + high = (struct stack_frame *) > + ((unsigned long) tsk->thread_info + THREAD_SIZE) - 1; > + sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN); > + if (sf <= low || sf > high) > + return 0; > + sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN); > + if (sf <= low || sf > high) > + return 0; > return sf->gprs[8]; > } > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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