From 4bdd347ccefaa114fa5bcf425301bfc8e8eae753 Mon Sep 17 00:00:00 2001
From: Ross Lagerwall <ross.lagerwall@citrix.com>
Date: Mon, 9 May 2016 11:19:54 +0100
Subject: [PATCH] Fix patching functions which use __func__

If __func__ is used, it generates a symbol like __func__.5432
Since this is always included (see is_special_static), it will generate
duplicate symbol conflicts if GCC happens to use the same number (which
happens quite often since it doesn't appear to be random). To work
around this, rename the symbol to use a completely random number.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
---
 create-diff-object.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/create-diff-object.c b/create-diff-object.c
index 37f3740..7d3824b 100644
--- a/create-diff-object.c
+++ b/create-diff-object.c
@@ -36,6 +36,7 @@
  * the output object.
  */
 
+#define _GNU_SOURCE
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -45,6 +46,7 @@
 #include <argp.h>
 #include <error.h>
 #include <unistd.h>
+#include <time.h>
 #include <gelf.h>
 
 #include "list.h"
@@ -1521,6 +1523,23 @@ static void kpatch_build_strings_section_data(struct kpatch_elf *kelf)
 	}
 }
 
+/*
+ * If __func__ is used, it generates a symbol like __func__.5432
+ * Since this is always included (see is_special_static), it will generate
+ * duplicate symbol conflicts if GCC happens to use the same number (which
+ * happens quite often since it doesn't appear to be random). To work around
+ * this, rename the symbol to use a completely random number.
+ */
+static char *rename_func_symbol(void)
+{
+	char *s;
+
+	if (asprintf(&s, "__func__.%d", rand()) == -1)
+		ERROR("malloc");
+
+	return s;
+}
+
 static char *mangle_local_symbol(char *filename, char *symname)
 {
 	char *s, *ptr;
@@ -1556,6 +1575,8 @@ static void xsplice_rename_local_symbols(struct kpatch_elf *kelf, char *hint)
 		if (sym->bind != STB_LOCAL)
 			continue;
 
+                if (!strncmp(sym->name, "__func__.", 9))
+                    sym->name = rename_func_symbol();
 		sym->name = mangle_local_symbol(hint, sym->name);
 		log_debug("Local symbol mangled to: %s\n", sym->name);
 	}
@@ -1824,6 +1845,8 @@ int main(int argc, char *argv[])
 	struct symbol *sym;
 	char *hint = NULL;
 
+	srand(time(NULL));
+
 	arguments.debug = 0;
 	arguments.resolve = 0;
 	argp_parse (&argp, argc, argv, 0, 0, &arguments);
-- 
2.39.5