Messages in this thread Patch in this message | | | Date | Thu, 12 Jan 2006 18:15:16 +0100 | From | Martin Schwidefsky <> | Subject | [patch 5/13] s390: show_task oops. |
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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.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
arch/s390/kernel/process.c | 15 ++++++++++++--- 1 files changed, 12 insertions(+), 3 deletions(-)
diff -urpN linux-2.6/arch/s390/kernel/process.c linux-2.6-patched/arch/s390/kernel/process.c --- 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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