Messages in this thread | | | Date | Sat, 25 Feb 2006 23:10:39 +0100 (MET) | From | Jan Engelhardt <> | Subject | Re: Mapping to 0x0 |
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>> I am playing around with it. I did the attached code. It is a usermode >> program, which tries to map NULL, and a kernel module, which calls a NULL >> pointer. The file badcode.bin contains an i386 ud2 instruction. When >> loading the kernel module, while the usermode program is executing, I get >> the usual NULL pointer dereference oops: > > You need to trigger the null pointer dereference from within the userspace > program that maps NULL. The reason your test doesn't do anything is that it is > the insmod tool whose address space gets used, as opposed to your nulltest > program. >
Think of a device driver which dereferences on read() or write() or ioctl. Then the userspace program gets its chance, does not it?
Jan Engelhardt -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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