iOS Kernel Heap Armageddon - Hakim
iOS Kernel Heap Armageddon - Hakim iOS Kernel Heap Armageddon - Hakim
iOS Kernel Zone Allocator 101 • zone allocator keeps a single linked list of free blocks • last memory block is first in freelist - memory is allocated backwards 0x000 0x200 0x400 0x600 0x800 0xA00 0xC00 0xE00 0x1000 head of freelist Stefan Esser • iOS Kernel Heap Armageddon REVISITED • July 2012 • 12
iOS Kernel Zone Allocator 101 • when memory is allocated the head of the freelist is returned • and the pointer stored in the free memory block is made the new head before allocation after allocation head of freelist head of freelist Stefan Esser • iOS Kernel Heap Armageddon REVISITED • July 2012 • 13
- Page 1 and 2: http://www.sektioneins.de iOS Kerne
- Page 3 and 4: DISCLAIMER iOS 6 • is in beta =>
- Page 5 and 6: So what is this talk about? • zon
- Page 7 and 8: Some Kernel Zones $ zprint kalloc e
- Page 9 and 10: iOS Kernel Zone Allocator 101 • k
- Page 11: iOS Kernel Zone Allocator 101 • z
- Page 15 and 16: Exploiting the freelist in iOS 6
- Page 17 and 18: Overview Managers and Wrappers not
- Page 19 and 20: kalloc() • kalloc() is a wrapper
- Page 21 and 22: kfree() • kfree() is a bit specia
- Page 23 and 24: _MALLOC() • _MALLOC() is a wrappe
- Page 25 and 26: _MALLOC() in iOS 5.x void *_MALLOC(
- Page 27 and 28: What about kern_os_malloc(), new an
- Page 29 and 30: mcache / slab could and might fill
- Page 31 and 32: kernel_memory_allocate • “maste
- Page 33 and 34: Cross Zone Attacks • what is the
- Page 35 and 36: Visualization of Zone Page Allocati
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<strong>iOS</strong> <strong>Kernel</strong> Zone Allocator 101<br />
• when memory is allocated the head of the freelist is returned<br />
• and the pointer stored in the free memory block is made the new head<br />
before<br />
allocation<br />
after<br />
allocation<br />
head of freelist<br />
head of freelist<br />
Stefan Esser • <strong>iOS</strong> <strong>Kernel</strong> <strong>Heap</strong> <strong>Armageddon</strong> REVISITED • July 2012 •<br />
13
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