Re: [Libguestfs] [PATCH nbdkit v2 1/2] tests: Invoke MALLOC_CHECK_ correctly and only for glibc

MALLOC_CHECK_ and MALLOC_PERTURB_ environment variables have been replaced in glibc 2.34 by GLIBC_TUNABLES settings[1][2]. In addition the new glibc requires that you preload a new library called libc_malloc_debug.so.0 to get these features.

These features never worked in non-glibc (but the environment variables are ignored). Only define MALLOC_* environment variables when we detect glibc < 2.34, using the ordinary glibc macros[3]. For glibc >= 2.34, use the new library and GLIBC_TUNABLES. Note this relies on LD_PRELOAD warning but otherwise not breaking if a preload library does not exist. [1] https://www.gnu.org/software/libc/manual/html_node/Memory-Allocation-Tuna... [2] https://sourceware.org/pipermail/libc-alpha/2021-August/129718.html [3] https://sourceforge.net/p/predef/wiki/Libraries/ Thanks: Eric Blake --- +# Enable malloc-check as a cheap way to find some use-after-free and +# uninitialized read problems when using glibc, and doesn't affect +# normal operation or other libc. +random = $(shell bash -c 'echo $$(( 1 + (RANDOM & 255) ))') +if HAVE_GLIBC_234 +TESTS_ENVIRONMENT += \ + LD_PRELOAD="$${LD_PRELOAD:+"$$LD_PRELOAD:"}$(libdir)/libc_malloc_debug.so.0" \ + GLIBC_TUNABLES=glibc.malloc.check=1:glibc.malloc.perturb=$(random) \ + $(NULL)