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[David Keaton <dmk AT dmk.com>]

     I tried the version of SAFECode that works with the LLVM 3.0 
release, and I got a puzzling result.  I'm hoping you have seen this before.

     I used svn to check out the release_30 branch of LLVM (not the 
trunk) and put poolalloc and safecode in the projects directory.  I 
built it following the directions on the SAFECode web site.  I did this 
on Ubuntu 10.04 x86-64.

     Then I copied and pasted the sample buffer overflow program from 
the SAFECode web site.

http://sva.cs.illinois.edu/docs/UsersGuide.html

     I used the following commands to compile and run it, pointing to 
the libraries I had just built as part of the SAFECode build.

clang -g -fmemsafety -o overflow overflow.c -L${HOME}/local/lib
./overflow 10

     The first part of the result was what I expected from reading the 
documentation.  Then a repeating attempted null pointer dereference 
occurred, and SAFECode didn't seem to be able to find out where it came 
from.

SAFECode:Violation Type 0x6 when accessing  0x170eda9 at IP=0x4025ea

=======+++++++    SAFECODE RUNTIME ALERT +++++++=======
= Error type                            :       Load/Store Error
= Faulting pointer                      :       0x170eda9
= Program counter                       :       0x4025ea
= Fault PC Source                       :       
/home/dmk/com/llvm/sample/overfl
ow.c:7
=
= Object allocated at PC                :       0x402d15
= Allocated in Source File              :       
/home/dmk/com/llvm/sample/overfl
ow.c:17
= Object allocation sequence number     :       3
= Object start                          :       0x170eda0
= Object length                         :       0x9
SAFECode: Fault!
SAFECode:Violation Type 0x9 when accessing  0xc0000001 at IP=0x8

=======+++++++    SAFECODE RUNTIME ALERT +++++++=======
= Error type                            :       Uninitialized/NULL Pointer 
Error
= Faulting pointer                      :       0xc0000001
= Program counter                       :       0x8
= Fault PC Source                       :       <unknown>:0
SAFECode: Fault!
SAFECode:Violation Type 0x9 when accessing  0xc0000001 at IP=0x8

=======+++++++    SAFECODE RUNTIME ALERT +++++++=======
= Error type                            :       Uninitialized/NULL Pointer 
Error
= Faulting pointer                      :       0xc0000001
= Program counter                       :       0x8
= Fault PC Source                       :       <unknown>:0
SAFECode: Fault!
SAFECode:Violation Type 0x9 when accessing  0xc0000001 at IP=0x8

 . . .

     The null pointer dereference keeps reoccurring until I abort the 
program.

     Is this a known problem?  What is it that creates a null pointer 
dereference with a program counter of 0x8?

                                        David Keaton