Messages in this thread | | | From | Venu Byravarasu <> | Date | Fri, 17 Feb 2012 14:34:13 +0530 | Subject | RE: [PATCH] mm: mmap() sometimes succeeds even if the region to map is invalid. |
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> The detail of these problems is as follows:
> 1. mmap() succeeds even if "offset" argument is a negative value, although > it should return EINVAL in such case.
> In such case, it is actually regarded as big positive value > because the type of "off" is "unsigned long" in the kernel. > For example, off=-4096 (-0x1000) is regarded as > off = 0xfffffffffffff000 (x86_64) and as off = 0xfffff000 (x86). > It results in mapping too big offset region.
It is not true always.
Considering your example, say if page size is 4k, then PAGE_MASK = 0xFFF hence (off & ~PAGE_MASK) will be true and " -EINVAL" will be returned.
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