[RFC][PATCH 1/3] exec: Move unshare_files down to avoid locks being dropped on exec.

[Eric W. Biederman]

Signed-off-by: "Eric W. Biederman" <ebied...@xmission.com>
---
 fs/exec.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 1ebf6e5a521d..6f6167ec08eb 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1252,6 +1252,7 @@ void __set_task_comm(struct task_struct *tsk, const char 
*buf, bool exec)
  */
 int flush_old_exec(struct linux_binprm * bprm)
 {
+       struct files_struct *displaced;
        int retval;
 
        /*
@@ -1291,6 +1292,12 @@ int flush_old_exec(struct linux_binprm * bprm)
        flush_thread();
        current->personality &= ~bprm->per_clear;
 
+       retval = unshare_files(&displaced);
+       if (retval)
+               goto out;
+       if (displaced)
+               put_files_struct(displaced);
+
        /*
         * We have to apply CLOEXEC before we change whether the process is
         * dumpable (in setup_new_exec) to avoid a race with a process in 
userspace
@@ -1713,7 +1720,6 @@ static int __do_execve_file(int fd, struct filename 
*filename,
 {
        char *pathbuf = NULL;
        struct linux_binprm *bprm;
-       struct files_struct *displaced;
        int retval;
 
        if (IS_ERR(filename))
@@ -1735,14 +1741,10 @@ static int __do_execve_file(int fd, struct filename 
*filename,
         * further execve() calls fail. */
        current->flags &= ~PF_NPROC_EXCEEDED;
 
-       retval = unshare_files(&displaced);
-       if (retval)
-               goto out_ret;
-
        retval = -ENOMEM;
        bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
        if (!bprm)
-               goto out_files;
+               goto out_ret;
 
        retval = prepare_bprm_creds(bprm);
        if (retval)
@@ -1831,8 +1833,6 @@ static int __do_execve_file(int fd, struct filename 
*filename,
        kfree(pathbuf);
        if (filename)
                putname(filename);
-       if (displaced)
-               put_files_struct(displaced);
        return retval;
 
 out:
@@ -1849,9 +1849,6 @@ static int __do_execve_file(int fd, struct filename 
*filename,
        free_bprm(bprm);
        kfree(pathbuf);
 
-out_files:
-       if (displaced)
-               reset_files_struct(displaced);
 out_ret:
        if (filename)
                putname(filename);
-- 
2.17.1