genksyms: fix memory leak when the same symbol is read from *.symref file

When a symbol that is already registered is read again from *.symref
file, __add_symbol() removes the previous one from the hash table without
freeing it.

[Test Case]

  $ cat foo.c
  #include <linux/export.h>
  void foo(void);
  void foo(void) {}
  EXPORT_SYMBOL(foo);

  $ cat foo.symref
  foo void foo ( void )
  foo void foo ( void )

When a symbol is removed from the hash table, it must be freed along
with its ->name and ->defn members. However, sym->name cannot be freed
because it is sometimes shared with node->string, but not always. If
sym->name and node->string share the same memory, free(sym->name) could
lead to a double-free bug.

To resolve this issue, always assign a strdup'ed string to sym->name.

Fixes: 64e6c1e12372 ("genksyms: track symbol checksum changes")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/scripts/genksyms/genksyms.h b/scripts/genksyms/genksyms.h
index 21ed2ec2d98c..5621533dcb8e 100644
--- a/scripts/genksyms/genksyms.h
+++ b/scripts/genksyms/genksyms.h
@@ -32,7 +32,7 @@ struct string_list {
 
 struct symbol {
 	struct symbol *hash_next;
-	const char *name;
+	char *name;
 	enum symbol_type type;
 	struct string_list *defn;
 	struct symbol *expansion_trail;