Re: [PATCH] 2.4: Restore current->files in flush_old_exec

[Andreas Gruenbacher]

Here is an update ...

> On Sat, 9 Aug 2003, Herbert Xu wrote:
> > Yes but when you call unshare_files twice one of them will have to
> > copy.Index: linux-2.4.22-rc2.orig/fs/exec.c
===================================================================
--- linux-2.4.22-rc2.orig.orig/fs/exec.c	2003-08-09 04:44:07.000000000 +0200
+++ linux-2.4.22-rc2.orig/fs/exec.c	2003-08-09 05:04:35.000000000 +0200
@@ -582,8 +582,6 @@ int flush_old_exec(struct linux_binprm *
 	retval = unshare_files();
 	if(retval)
 		goto flush_failed;
-	steal_locks(files, current->files);
-	put_files_struct(files);
 	
 	/* 
 	 * Release all of the old mmap stuff
@@ -592,6 +590,8 @@ int flush_old_exec(struct linux_binprm *
 	if (retval) goto mmap_failed;
 
 	/* This is the point of no return */
+	steal_locks(files);
+	put_files_struct(files);
 	release_old_signals(oldsig);
 
 	current->sas_ss_sp = current->sas_ss_size = 0;
@@ -629,6 +629,8 @@ int flush_old_exec(struct linux_binprm *
 	return 0;
 
 mmap_failed:
+	put_files_struct(current->files);
+	current->files = files;
 flush_failed:
 	spin_lock_irq(&current->sigmask_lock);
 	if (current->sig != oldsig) {
Index: linux-2.4.22-rc2.orig/include/linux/fs.h
===================================================================
--- linux-2.4.22-rc2.orig.orig/include/linux/fs.h	2003-08-09 04:44:07.000000000 +0200
+++ linux-2.4.22-rc2.orig/include/linux/fs.h	2003-08-09 05:04:35.000000000 +0200
@@ -674,7 +674,7 @@ extern int __get_lease(struct inode *ino
 extern time_t lease_get_mtime(struct inode *);
 extern int lock_may_read(struct inode *, loff_t start, unsigned long count);
 extern int lock_may_write(struct inode *, loff_t start, unsigned long count);
-extern void steal_locks(fl_owner_t from, fl_owner_t to);
+extern void steal_locks(fl_owner_t from);
 
 struct fasync_struct {
 	int	magic;
Index: linux-2.4.22-rc2.orig/fs/binfmt_elf.c
===================================================================
--- linux-2.4.22-rc2.orig.orig/fs/binfmt_elf.c	2003-08-09 04:44:07.000000000 +0200
+++ linux-2.4.22-rc2.orig/fs/binfmt_elf.c	2003-08-09 05:06:05.000000000 +0200
@@ -444,7 +444,7 @@ static int load_elf_binary(struct linux_
 	struct elfhdr interp_elf_ex;
   	struct exec interp_ex;
 	char passed_fileno[6];
-	struct files_struct *files, *ftmp;
+	struct files_struct *files;
 	
 	/* Get the exec-header */
 	elf_ex = *((struct elfhdr *) bprm->buf);
@@ -480,7 +480,10 @@ static int load_elf_binary(struct linux_
 	files = current->files;		/* Refcounted so ok */
 	if(unshare_files() < 0)
 		goto out_free_ph;
-	steal_locks(files, current->files);
+	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 */
@@ -603,7 +606,11 @@ static int load_elf_binary(struct linux_
 		goto out_free_dentry;
 
 	/* Discard our unneeded old files struct */
-	put_files_struct(files);
+	if (files) {
+		steal_locks(files);
+		put_files_struct(files);
+		files = NULL;
+	}
 
 	/* OK, This is the point of no return */
 	current->mm->start_data = 0;
@@ -714,18 +721,16 @@ static int load_elf_binary(struct linux_
 			elf_entry = load_elf_interp(&interp_elf_ex,
 						    interpreter,
 						    &interp_load_addr);
-
-		allow_write_access(interpreter);
-		fput(interpreter);
-		kfree(elf_interpreter);
-
 		if (BAD_ADDR(elf_entry)) {
 			printk(KERN_ERR "Unable to load interpreter\n");
-			kfree(elf_phdata);
 			send_sig(SIGSEGV, current, 0);
 			retval = -ENOEXEC; /* Nobody gets to see this, but.. */
-			goto out;
+			goto out_free_dentry;
 		}
+
+		allow_write_access(interpreter);
+		fput(interpreter);
+		kfree(elf_interpreter);
 	}
 
 	kfree(elf_phdata);
@@ -811,10 +816,10 @@ out_free_interp:
 out_free_file:
 	sys_close(elf_exec_fileno);
 out_free_fh:
-	ftmp = current->files;
-	current->files = files;
-	steal_locks(ftmp, current->files);
-	put_files_struct(ftmp);
+	if (files) {
+		put_files_struct(current->files);
+		current->files = files;
+	}
 out_free_ph:
 	kfree(elf_phdata);
 	goto out;
Index: linux-2.4.22-rc2.orig/fs/locks.c
===================================================================
--- linux-2.4.22-rc2.orig.orig/fs/locks.c	2003-08-09 04:44:07.000000000 +0200
+++ linux-2.4.22-rc2.orig/fs/locks.c	2003-08-09 05:04:35.000000000 +0200
@@ -1937,11 +1937,11 @@ done:
 	return length;
 }
 
-void steal_locks(fl_owner_t from, fl_owner_t to)
+void steal_locks(fl_owner_t from)
 {
 	struct list_head *tmp;
 
-	if (from == to)
+	if (from == current->files)
 		return;
 
 	lock_kernel();
@@ -1949,7 +1949,7 @@ void steal_locks(fl_owner_t from, fl_own
 		struct file_lock *fl = list_entry(tmp, struct file_lock,
 						  fl_link);
 		if (fl->fl_owner == from)
-			fl->fl_owner = to;
+			fl->fl_owner = current->files;
 	}
 	unlock_kernel();
 }