[PATCH] sanitize handling of shared descriptor tables in failing execve()

* unshare_files() can fail; doing it after irreversible actions is wrong
  and de_thread() is certainly irreversible.
* since we do it unconditionally anyway, we might as well do it in do_execve()
  and save ourselves the PITA in binfmt handlers, etc.
* while we are at it, binfmt_som actually leaked files_struct on failure.

As a side benefit, unshare_files(), put_files_struct() and reset_files_struct()
become unexported.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 0 insertions, 5 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index cece89f80ab4..3d320003cc03 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -507,8 +507,6 @@ void put_files_struct(struct files_struct *files)
         }
 }
 
-EXPORT_SYMBOL(put_files_struct);
-
 void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
 {
         struct files_struct *old;
@@ -519,7 +517,6 @@ void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
         task_unlock(tsk);
         put_files_struct(old);
 }
-EXPORT_SYMBOL(reset_files_struct);
 
 void exit_files(struct task_struct *tsk)
 {
diff --git a/kernel/fork.c b/kernel/fork.c
index 76f05a08062b..2fc11f2e2b21 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -870,8 +870,6 @@ int unshare_files(void)
         return error;
 }
 
-EXPORT_SYMBOL(unshare_files);
-
 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
 {
         struct sighand_struct *sig;