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authorAvi Kivity <avi@qumranet.com>2010-01-10 16:28:09 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2010-01-11 09:45:37 -0800
commita29815a333c6c6e677294bbe5958e771d0aad3fd (patch)
tree589a782f1992a7da55469379688deaa9f355b779 /Documentation
parentc0f607c608ba889db5250235ba620f818aa44a4d (diff)
downloadvexpress-lsk-a29815a333c6c6e677294bbe5958e771d0aad3fd.tar.gz
core, x86: make LIST_POISON less deadly
The list macros use LIST_POISON1 and LIST_POISON2 as undereferencable pointers in order to trap erronous use of freed list_heads. Unfortunately userspace can arrange for those pointers to actually be dereferencable, potentially turning an oops to an expolit. To avoid this allow architectures (currently x86_64 only) to override the default values for these pointers with truly-undereferencable values. This is easy on x86_64 as the virtual address space is large and contains areas that cannot be mapped. Other 64-bit architectures will likely find similar unmapped ranges. [ingo: switch to 0xdead000000000000 as the unmapped area] [ingo: add comments, cleanup] [jaswinder: eliminate sparse warnings] Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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