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SubjectRe: BUG: bad usercopy in memdup_user
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On 12/19/2017 01:48 PM, Al Viro wrote:
> On Tue, Dec 19, 2017 at 01:36:46PM -0800, Linus Torvalds wrote:
>
>> I suspect that an "offset and size within the kernel object" value
>> might make sense. But what does the _pointer_ tell you?
>
> Well, for example seeing a 0xfffffffffffffff4 where a pointer to object
> must have been is a pretty strong hint to start looking for a way for
> that ERR_PTR(-ENOMEM) having ended up there... Something like
> 0x6e69622f7273752f is almost certainly a misplaced "/usr/bin", i.e. a

possibly poison values also?

> pathname overwriting whatever it ends up in, etc. And yes, I have run
> into both of those in real life.
>
> Debugging the situation when crap value has ended up in place of a
> pointer is certainly a case where you do want to see what exactly has
> ended up in there...


--
~Randy

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