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CVS commit: src/sys/uvm

Module Name:    src
Committed By:   drochner
Date:           Thu Feb 18 14:57:01 UTC 2010

Modified Files:
        src/sys/uvm: files.uvm uvm_map.c

Log Message:
Disable mapping of virtual address 0 by user programs per default.
This blocks an easy exploit of kernel bugs leading to dereference
of a NULL pointer on some architectures (eg i386).
The check can be disabled in various ways:
-by CPP definitions in machine/types.h (portmaster's choice)
-by a kernel config option USER_VA0_DISABLED_DEFAULT=0
-at runtime by sysctl vm.user_va0_disabled (cannot be cleared
 at securelevel>0)

To generate a diff of this commit:
cvs rdiff -u -r1.16 -r1.17 src/sys/uvm/files.uvm
cvs rdiff -u -r1.287 -r1.288 src/sys/uvm/uvm_map.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

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