http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55289
--- Comment #14 from Jack Howarth <howarth at nitro dot med.uc.edu> 2012-11-13 20:50:37 UTC --- Actually, this appears to be just noise on the output from a functional libasan. If I use the testcase from http://code.google.com/p/address-sanitizer/wiki/AddressSanitizer of... % cat tests/use-after-free.c #include <stdlib.h> int main() { char *x = (char*)malloc(10 * sizeof(char*)); free(x); return x[5]; } I get... howarth% gcc-fsf-4.8 -faddress-sanitizer -framework CoreFoundation -O1 -fno-omit-frame-pointer -g use-after-free.c -lasan howarth% ./a.out mach_override: some instructions unknown! Need to update mach_override.c err = f8000001 ../../../../gcc-4.8-20121113/libsanitizer/interception/mach_override/mach_override.c:308 err = f8000001 ../../../../gcc-4.8-20121113/libsanitizer/interception/mach_override/mach_override.c:321 err = f8000001 ../../../../gcc-4.8-20121113/libsanitizer/interception/mach_override/mach_override.c:327 err = f8000001 ../../../../gcc-4.8-20121113/libsanitizer/interception/mach_override/mach_override.c:340 err = f8000001 ../../../../gcc-4.8-20121113/libsanitizer/interception/mach_override/mach_override.c:345 ================================================================= ==88551== ERROR: AddressSanitizer heap-use-after-free on address 0x000105cbaf45 at pc 0x103001f12 bp 0x7fff5cbfe8f0 sp 0x7fff5cbfe8e8 READ of size 1 at 0x000105cbaf45 thread T0 #0 0x103001f11 (/Users/howarth/./a.out+0x100000f11) #1 0x7fff8bd827e0 (/usr/lib/system/libdyld.dylib+0x27e0) #2 0x0 0x000105cbaf45 is located 5 bytes inside of 80-byte region [0x000105cbaf40,0x000105cbaf90) freed by thread T0 here: #0 0x1030147a4 (/sw/lib/gcc4.8/lib/libasan.0.dylib+0xb7a4) #1 0x10301492a (/sw/lib/gcc4.8/lib/libasan.0.dylib+0xb92a) #2 0x103001ee5 (/Users/howarth/./a.out+0x100000ee5) #3 0x7fff8bd827e0 (/usr/lib/system/libdyld.dylib+0x27e0) #4 0x0 previously allocated by thread T0 here: #0 0x103014255 (/sw/lib/gcc4.8/lib/libasan.0.dylib+0xb255) #1 0x7fff94c3b152 (/usr/lib/system/libsystem_c.dylib+0x2d152) #2 0x7fff94c3bba6 (/usr/lib/system/libsystem_c.dylib+0x2dba6) #3 0x103001eda (/Users/howarth/./a.out+0x100000eda) #4 0x7fff8bd827e0 (/usr/lib/system/libdyld.dylib+0x27e0) Shadow byte and word: 0x100020b975e8: fd 0x100020b975e8: fd fd fd fd fd fd fd fd More shadow bytes: 0x100020b975c8: fa fa fa fa fa fa fa fa 0x100020b975d0: fa fa fa fa fa fa fa fa 0x100020b975d8: fa fa fa fa fa fa fa fa 0x100020b975e0: fa fa fa fa fa fa fa fa =>0x100020b975e8: fd fd fd fd fd fd fd fd 0x100020b975f0: fd fd fd fd fd fd fd fd 0x100020b975f8: fa fa fa fa fa fa fa fa 0x100020b97600: fa fa fa fa fa fa fa fa 0x100020b97608: fa fa fa fa fa fa fa fa Stats: 0M malloced (0M for red zones) by 1 calls Stats: 0M realloced by 0 calls Stats: 0M freed by 1 calls Stats: 0M really freed by 0 calls Stats: 0M (128 full pages) mmaped in 1 calls mmaps by size class: 8:2047; mallocs by size class: 8:1; frees by size class: 8:1; rfrees by size class: Stats: malloc large: 0 small slow: 1 ==88551== ABORTING compared to... howarth% /sw/opt/llvm-3.2/bin/clang -fsanitize=address -O1 -fno-omit-frame-pointer -g use-after-free.c howarth% ./a.out ================================================================= ==88537== ERROR: AddressSanitizer: heap-use-after-free on address 0x00010a0a2f45 at pc 0x107dcae54 bp 0x7fff57e358f0 sp 0x7fff57e358e8 READ of size 1 at 0x00010a0a2f45 thread T0 #0 0x107dcae53 (/Users/howarth/./a.out+0x100000e53) #1 0x7fff8bd827e0 (/usr/lib/system/libdyld.dylib+0x27e0) #2 0x0 0x00010a0a2f45 is located 5 bytes inside of 80-byte region [0x00010a0a2f40,0x00010a0a2f90) freed by thread T0 here: #0 0x107dd3878 (/Users/howarth/./a.out+0x100009878) #1 0x107dd2ef2 (/Users/howarth/./a.out+0x100008ef2) #2 0x107dcae1a (/Users/howarth/./a.out+0x100000e1a) #3 0x7fff8bd827e0 (/usr/lib/system/libdyld.dylib+0x27e0) #4 0x0 previously allocated by thread T0 here: #0 0x107dd3682 (/Users/howarth/./a.out+0x100009682) #1 0x7fff94c3b152 (/usr/lib/system/libsystem_c.dylib+0x2d152) #2 0x7fff94c3bba6 (/usr/lib/system/libsystem_c.dylib+0x2dba6) #3 0x107dcae0f (/Users/howarth/./a.out+0x100000e0f) #4 0x7fff8bd827e0 (/usr/lib/system/libdyld.dylib+0x27e0) Shadow byte and word: 0x1000214145e8: fd 0x1000214145e8: fd fd fd fd fd fd fd fd More shadow bytes: 0x1000214145c8: fa fa fa fa fa fa fa fa 0x1000214145d0: fa fa fa fa fa fa fa fa 0x1000214145d8: fa fa fa fa fa fa fa fa 0x1000214145e0: fa fa fa fa fa fa fa fa =>0x1000214145e8: fd fd fd fd fd fd fd fd 0x1000214145f0: fd fd fd fd fd fd fd fd 0x1000214145f8: fa fa fa fa fa fa fa fa 0x100021414600: fa fa fa fa fa fa fa fa 0x100021414608: fa fa fa fa fa fa fa fa Stats: 0M malloced (0M for red zones) by 1 calls Stats: 0M realloced by 0 calls Stats: 0M freed by 1 calls Stats: 0M really freed by 0 calls Stats: 0M (128 full pages) mmaped in 1 calls mmaps by size class: 8:2047; mallocs by size class: 8:1; frees by size class: 8:1; rfrees by size class: Stats: malloc large: 0 small slow: 1 ==88537== ABORTING
