From 641f77e53c86ad7eaa15138984ce39471689b1d9 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Wed, 23 Mar 2022 09:57:19 -0700 Subject: [PATCH v2 1/3] Add a hacky workaround to make ubsan and ps_status.c compatible At least on linux set_ps_display() breaks /proc/$pid/environ. The sanitizer library uses /proc/$pid/environ to implement getenv() because it wants to work independent of libc. When just using undefined and alignment sanitizers, the sanitizer library is only initialized when the first error occurs, by which time we've often already called set_ps_display(), preventing the sanitizer libraries from seeing the options. We can work around that by defining __ubsan_default_options, a weak symbol libsanitizer uses to get defaults from the application, and return getenv("UBSAN_OPTIONS"). But only if main already was reached, so that we don't end up relying on a not-yet-working getenv(). As it's just a function that won't get called when not running a sanitizer, it doesn't seem necessary to make compilation of the function conditional. Reviewed-by: Tom Lane Discussion: https://postgr.es/m/20220323173537.ll7klrglnp4gn2um@alap3.anarazel.de --- src/backend/main/main.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/src/backend/main/main.c b/src/backend/main/main.c index f5da4260a13..16bcf045ae6 100644 --- a/src/backend/main/main.c +++ b/src/backend/main/main.c @@ -43,6 +43,7 @@ const char *progname; +static bool reached_main = false; static void startup_hacks(const char *progname); @@ -59,6 +60,8 @@ main(int argc, char *argv[]) { bool do_check_root = true; + reached_main = true; + /* * If supported on the current platform, set up a handler to be called if * the backend/postmaster crashes with a fatal signal or exception. @@ -421,3 +424,27 @@ check_root(const char *progname) } #endif /* WIN32 */ } + +/* + * At least on linux set_ps_display() breaks /proc/$pid/environ. The sanitizer + * library uses /proc/$pid/environ to implement getenv() because it wants to + * work independent of libc. When just using undefined and alignment + * sanitizers, the sanitizer library is only initialized when the first error + * occurs, by which time we've often already called set_ps_display(), + * preventing the sanitizer libraries from seeing the options. + * + * We can work around that by defining __ubsan_default_options, a weak symbol + * libsanitizer uses to get defaults from the application, and return + * getenv("UBSAN_OPTIONS"). But only if main already was reached, so that we + * don't end up relying on a not-yet-working getenv(). + */ +const char *__ubsan_default_options(void); +const char * +__ubsan_default_options(void) +{ + /* don't call libc before it's initialized */ + if (!reached_main) + return ""; + + return getenv("UBSAN_OPTIONS"); +} -- 2.37.3.542.gdd3f6c4cae