From c331d73b3e03853aa7a8a7bed273f11aebda4ee6 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Mon, 31 Aug 2026 17:25:39 +0000 Subject: [PATCH] trace2: remove use of xstrdup() In the previous change, we removed a use of xsprintf() that caused a recursive die() loop when failing to allocate memory. The trace2 library is too low-level to be calling die(), especially because of these recursive loops that can occur during the die handler. For full defense in depth, we remove the xstrdup() calls from trace2/tr2_sysenv.c. First, in tr2_sysenv_cb(), we need to handle a failed assignment of the value with a zero-valued return to halt the config parsing loop. Note that we don't want to use a negative return here or we would imply to the config system that the config key or value was somehow invalid; such an output would mask the real issue that the process failed to allocate memory. Second, in tr2_sysenv_get(), the method will return NULL when strdup() returns NULL. This return is indistinguishable from the environment variable having no value. That means that all callers know how to handle a NULL response, but no behavior change will occur between the case of no environment being set and detecting an environment variable exists but we fail to duplicate it. This seems an appropriate trade-off, as an allocation failure at this level will likely lead to failure in another system, but at least the trace2 API will not cause the process to fail early. Helped-by: Elijah Newren Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano --- banned-die.h | 3 +++ trace2/tr2_sysenv.c | 6 ++++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/banned-die.h b/banned-die.h index 589e9cc2bd..bf16ec5ba9 100644 --- a/banned-die.h +++ b/banned-die.h @@ -14,4 +14,7 @@ #undef xsnprintf #define xsnprintf(...) BANNED(xsnprintf) +#undef xstrdup +#define xstrdup(str) BANNED(xstrdup) + #endif /* BANNED_DIE_H */ diff --git a/trace2/tr2_sysenv.c b/trace2/tr2_sysenv.c index 7fa58eba91..4a9983caf4 100644 --- a/trace2/tr2_sysenv.c +++ b/trace2/tr2_sysenv.c @@ -75,7 +75,9 @@ static int tr2_sysenv_cb(const char *key, const char *value, if (!value) return config_error_nonbool(key); free(tr2_sysenv_settings[k].value); - tr2_sysenv_settings[k].value = xstrdup(value); + tr2_sysenv_settings[k].value = strdup(value); + if (!tr2_sysenv_settings[k].value) + return 0; return 0; } } @@ -111,7 +113,7 @@ const char *tr2_sysenv_get(enum tr2_sysenv_variable var) const char *v = getenv(tr2_sysenv_settings[var].env_var_name); if (v && *v) { free(tr2_sysenv_settings[var].value); - tr2_sysenv_settings[var].value = xstrdup(v); + tr2_sysenv_settings[var].value = strdup(v); } tr2_sysenv_settings[var].getenv_called = 1; }