Messages in this thread | | | From | Linus Torvalds <> | Date | Thu, 8 Mar 2018 08:45:19 -0800 | Subject | Re: [PATCH] vsprintf: Make "null" pointer dereference more robust |
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On Thu, Mar 8, 2018 at 6:18 AM, Petr Mladek <pmladek@suse.com> wrote: > On Wed 2018-03-07 10:34:17, Linus Torvalds wrote: >> >> Guess what happens now to any crash report if it uses %p and there is >> anything wrong with the VM? > > This patch does _not_ affect plain %p, %px, and %pK!
Umm. Look again. It _does_ affect plain %p.
You're correct that it doesn't affect %px and %pK, since those never printed out (null) in the first place.
> It affects %s and %p* modifiers that need to read data from the > given address.
_If_ that was what the patch did, it would be fine.
But it isn't.
It not only affects %p, but it also affects %pS and friends (sSfFB), that do not access the location (well, on some architectures those might, to dereference a function descriptor, but then they will check the address range).
So that patch really is completely broken for the reasons I outlined.
Now, if it was fixed to what you apparently *intended* to do, then that would be ok.
Linus
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