[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>
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 5e1a4fb..9924581 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -543,7 +543,6 @@
unsigned long interp_load_addr = 0;
unsigned long start_code, end_code, start_data, end_data;
unsigned long reloc_func_desc = 0;
- struct files_struct *files;
int executable_stack = EXSTACK_DEFAULT;
unsigned long def_flags = 0;
struct {
@@ -593,20 +592,9 @@
goto out_free_ph;
}
- files = current->files; /* Refcounted so ok */
- retval = unshare_files();
- if (retval < 0)
- goto out_free_ph;
- if (files == current->files) {
- put_files_struct(files);
- files = NULL;
- }
-
- /* exec will make our files private anyway, but for the a.out
- loader stuff we need to do it earlier */
retval = get_unused_fd();
if (retval < 0)
- goto out_free_fh;
+ goto out_free_ph;
get_file(bprm->file);
fd_install(elf_exec_fileno = retval, bprm->file);
@@ -728,12 +716,6 @@
if (retval)
goto out_free_dentry;
- /* Discard our unneeded old files struct */
- if (files) {
- put_files_struct(files);
- files = NULL;
- }
-
/* OK, This is the point of no return */
current->flags &= ~PF_FORKNOEXEC;
current->mm->def_flags = def_flags;
@@ -1016,9 +998,6 @@
kfree(elf_interpreter);
out_free_file:
sys_close(elf_exec_fileno);
-out_free_fh:
- if (files)
- reset_files_struct(current, files);
out_free_ph:
kfree(elf_phdata);
goto out;