coreutils-9.4.170-7b206 undefined behaviour in tests

[Bruno Haible]

Hi,

Building coreutils-9.4.170-7b206 on a glibc system, with clang and ASAN and
UBSAN options, produces 4 test failures.

I'm using clang 17.0.4 with the options
CC="$CC 
-fsanitize=address,undefined,signed-integer-overflow,shift,integer-divide-by-zero"
CFLAGS="-O0 -fno-omit-frame-pointer -ggdb"
ASAN_OPTIONS="detect_leaks=0 abort_on_error=1 allocator_may_return_null=1"

The failing tests are:

FAIL: tests/misc/comm.pl
FAIL: tests/join/join.pl
FAIL: tests/uniq/uniq.pl
FAIL: tests/ls/removed-directory.sh

In the test-suite.log file there are hundreds of occurrences of

+ ../lib/linebuffer.c:65:22: runtime error: applying zero offset to null pointer
+ SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior 
../lib/linebuffer.c:65:22 in 

and 1 occurrence of

+../lib/mpsort.c:155:34: runtime error: applying zero offset to null pointer
+SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ../lib/mpsort.c:155:34 
in 

I have proposed a fix for this in
<https://lists.gnu.org/archive/html/bug-gnulib/2023-12/msg00055.html>,
but Paul Eggert opposes it.

Bruno