Comment 0 for bug 2048768

Some tests related to the address sanitizer are occasionally failing on amd64 (also for llvm-toolchain-15):

--------------
FAIL: LLVM regression suite :: test_leaksan.c (38 of 45)
746s ******************** TEST 'LLVM regression suite :: test_leaksan.c' FAILED ********************
746s Script:
746s --
746s : 'RUN: at line 4'; /usr/bin/clang-14 -o /tmp/autopkgtest.gHVujV/autopkgtest_tmp/build/tests/Output/test_leaksan.c.tmp -fsanitize=address -g /tmp/autopkgtest.gHVujV/autopkgtest_tmp/tests/test_leaksan.c
746s : 'RUN: at line 5'; env ASAN_OPTIONS="log_path=stdout:exitcode=0" /tmp/autopkgtest.gHVujV/autopkgtest_tmp/build/tests/Output/test_leaksan.c.tmp 2>&1 > /tmp/autopkgtest.gHVujV/autopkgtest_tmp/build/tests/Output/test_leaksan.c.tmp.out
746s : 'RUN: at line 6'; grep -q "detected memory leaks" /tmp/autopkgtest.gHVujV/autopkgtest_tmp/build/tests/Output/test_leaksan.c.tmp.out
746s --
746s Exit Code: 139
746s
746s Command Output (stderr):
746s --
746s /tmp/autopkgtest.gHVujV/autopkgtest_tmp/build/tests/Output/test_leaksan.c.script: line 3: 3335 Segmentation fault (core dumped) env ASAN_OPTIONS="log_path=stdout:exitcode=0" /tmp/autopkgtest.gHVujV/autopkgtest_tmp/build/tests/Output/test_leaksan.c.tmp 2>&1 > /tmp/autopkgtest.gHVujV/autopkgtest_tmp/build/tests/Output/test_leaksan.c.tmp.out
--------------

If you run the test manually you'll notice that it works but eventually crashes:

--------------------
ubuntu@autopkgtest:/tmp/autopkgtest.oXC2FP/autopkgtest_tmp/build/tests/Output$ ./test_leaksan.c.tmp

=================================================================
==8631==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 7 byte(s) in 1 object(s) allocated from:
    #0 0x5e9c3441ed12 in __interceptor_malloc (/tmp/autopkgtest.oXC2FP/autopkgtest_tmp/build/tests/Output/test_leaksan.c.tmp+0xa3d12) (BuildId: 6f71ac388125722ade1ea86ee3661c0d884dd193)
    #1 0x5e9c3445acb8 in main /tmp/autopkgtest.oXC2FP/autopkgtest_tmp/tests/test_leaksan.c:13:7
    #2 0x7e84e1e280cf (/lib/x86_64-linux-gnu/libc.so.6+0x280cf) (BuildId: f0b834daa3d05a80967e9ec2f990a1ea71c958fa)

SUMMARY: AddressSanitizer: 7 byte(s) leaked in 1 allocation(s).
ubuntu@autopkgtest:/tmp/autopkgtest.oXC2FP/autopkgtest_tmp/build/tests/Output$ ./test_leaksan.c.tmp

=================================================================
==8634==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 7 byte(s) in 1 object(s) allocated from:
    #0 0x5f19be5f6d12 in __interceptor_malloc (/tmp/autopkgtest.oXC2FP/autopkgtest_tmp/build/tests/Output/test_leaksan.c.tmp+0xa3d12) (BuildId: 6f71ac388125722ade1ea86ee3661c0d884dd193)
    #1 0x5f19be632cb8 in main /tmp/autopkgtest.oXC2FP/autopkgtest_tmp/tests/test_leaksan.c:13:7
    #2 0x77c7d3c280cf (/lib/x86_64-linux-gnu/libc.so.6+0x280cf) (BuildId: f0b834daa3d05a80967e9ec2f990a1ea71c958fa)

SUMMARY: AddressSanitizer: 7 byte(s) leaked in 1 allocation(s).

ubuntu@autopkgtest:/tmp/autopkgtest.oXC2FP/autopkgtest_tmp/build/tests/Output$ ./test_leaksan.c.tmp
Segmentation fault (core dumped)
--------------------

After some investigation I found that it will not fail with ASLR disabled:

sudo sysctl kernel.randomize_va_space=0

while : ; do env ASAN_OPTIONS="log_path=stdout:exitcode=0" ./test_leaksan.c.tmp >/dev/null; if [ $? -ne 0 ] ; then echo crashed ; fi done

If you enable ASLR it will start to crash:

$ sudo sysctl kernel.randomize_va_space=2

$ while : ; do env ASAN_OPTIONS="log_path=stdout:exitcode=0" ./test_leaksan.c.tmp >/dev/null; if [ $? -ne 0 ] ; then echo crashed ; fi done
Segmentation fault (core dumped)
crashed
Segmentation fault (core dumped)
crashed
Segmentation fault (core dumped)
crashed
Segmentation fault (core dumped)
crashed
Segmentation fault (core dumped)
crashed

If you and ASLR again and run it with "setarch -R" (to disable ASLR for this binary), it will also not crash.