Messages in this thread | | | Date | Wed, 10 May 2017 10:14:53 +0800 | From | zhong jiang <> | Subject | Re: [RESENT PATCH] x86/mem: fix the offset overflow when read/write mem |
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On 2017/5/9 23:46, Rik van Riel wrote: > On Thu, 2017-05-04 at 10:28 +0800, zhong jiang wrote: >> On 2017/5/4 2:46, Rik van Riel wrote: >>> However, it is not as easy as simply checking the >>> end against __pa(high_memory). Some systems have >>> non-contiguous physical memory ranges, with gaps >>> of invalid addresses in-between. >> The invalid physical address means that it is used as >> io mapped. not in system ram region. /dev/mem is not >> access to them , is it right? > Not necessarily. Some systems simply have large > gaps in physical memory access. Their memory map > may look like this: > > |MMMMMM|IO|MMMM|..................|MMMMMMMM| > > Where M is memory, IO is IO space, and the > dots are simply a gap in physical address > space with no valid accesses at all. > >>> At that point, is the complexity so much that it no >>> longer makes sense to try to protect against root >>> crashing the system? >>> >> your suggestion is to let the issue along without any protection. >> just root user know what they are doing. > Well, root already has other ways to crash the system. > > Implementing validation on /dev/mem may make sense if > it can be done in a simple way, but may not be worth > it if it becomes too complex. > I have no a simple way to fix. Do you any suggestion. or you can send a patch for me ?
Thanks zhongjiang
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