Difference between revisions of "Memory layout"
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Binaries mapped by RO seems to be mapped randomly everywhere in the entire address space. The random base address for each NRO has bits 37-12 randomized, unlike the main binary region. | Binaries mapped by RO seems to be mapped randomly everywhere in the entire address space. The random base address for each NRO has bits 37-12 randomized, unlike the main binary region. | ||
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| + | For all binaries(main area / NROs), the R-- section is always located immediately after R-X. The RW- section is always located immediately after the R-- section. Hence, there's no extra randomization / guard-pages for these sections. | ||
Revision as of 22:54, 23 May 2017
Userspace
The userspace virtual address space has 38 bits. It seems that when the IPC protocol was designed, it was only 36 bits leading to a weird encoding format.
There are several regions maintained by the kernel, each one starting at the upper bits bit37-21 randomized:
- Main binary region.
- Heap region.
- Stack mapping region, available from SVC#svcGetInfo.
For the stack mapping region, the userland randomizes a page-offset where to start inside the region. This adds some additional entropy.
Binaries mapped by RO seems to be mapped randomly everywhere in the entire address space. The random base address for each NRO has bits 37-12 randomized, unlike the main binary region.
For all binaries(main area / NROs), the R-- section is always located immediately after R-X. The RW- section is always located immediately after the R-- section. Hence, there's no extra randomization / guard-pages for these sections.