Messages in this thread | | | Date | Tue, 14 May 2019 11:07:30 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH] vsprintf: Do not break early boot with probing addresses |
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On (05/13/19 14:42), Petr Mladek wrote: > > The "(null)" is good enough by itself and already an established > > practice.. > > (efault) made more sense with the probe_kernel_read() that > checked wide range of addresses. Well, I still think that > it makes sense to distinguish a pure NULL. And it still > used also for IS_ERR_VALUE().
Wouldn't anything within first PAGE_SIZE bytes be reported as a NULL deref?
char *p = (char *)(PAGE_SIZE - 2); *p = 'a';
gives
kernel: BUG: kernel NULL pointer dereference, address = 0000000000000ffe kernel: #PF: supervisor-privileged write access from kernel code kernel: #PF: error_code(0x0002) - not-present page
And I like Steven's "(fault)" idea. How about this:
if ptr < PAGE_SIZE -> "(null)" if IS_ERR_VALUE(ptr) -> "(fault)"
-ss
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