[PATCH v2 3/7] trace2: remove use of xstrdup()

From: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date: Aug 25, 2026, 18:56 UTC
Message-ID: <ec447a6a778a5c49344346df54b434a96c792082.1787684181.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.2178.v2.git.1787684181.gitgitgadget@gmail.com>

From: Derrick Stolee <stolee@gmail.com>

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 negative return to halt the config parsing loop.

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.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 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 0e0a794e5d..2e16c4899c 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 deb3fabff4..4ee273a4ae 100644
--- a/trace2/tr2_sysenv.c
+++ b/trace2/tr2_sysenv.c
@@ -74,7 +74,9 @@ 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 -1;
 			return 0;
 		}
 	}
@@ -110,7 +112,7 @@ 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;
 	}

-- 
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