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>

diff --git a/create-diff-object.c b/create-diff-object.c
index 37f3740b20ec91de45c38f34347f82fba3448ca4..7d3824bcf19a55cb92e739aefa3d3681f69839fa 100644 (file)
--- 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);