Messages in this thread | | | From | "Chen, Kenneth W" <> | Subject | RE: IA64 non-contiguous memory space bugs | Date | Tue, 21 Feb 2006 18:53:32 -0800 |
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David Gibson wrote on Tuesday, February 21, 2006 4:14 PM > First bug (confirmed many months ago by Chris Wedgwood) - you can get > weird effects if you attempt to mmap() something into one of the > address space gaps. The ia64 outer wrapper for mmap2() tries to > prevent it, but doesn't do a good enough job, it's still possible > indirectly with shmat() and maybe mremap(). Basic trouble is that > most of the checks applied by the generic code assume that everything > between 0 and TASK_SIZE is valid.
Ha ha ha.
On ia64, the low level tlb fault handler (vhpt_miss and nested_dtlb_miss) checks that all unused address bits (between REGION_NUMBER and PGDIR_SHIFT) should be all zero. If they are not zero, it will fall into page fault handler and in there, ia64 should just send SEGV instead of happily hand over a page. Buggy buggy....
- Ken
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