Patch "initramfs: finish fput() before accessing any binary from initramfs" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    initramfs: finish fput() before accessing any binary from initramfs

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     initramfs-finish-fput-before-accessing-any-binary-from-initramfs.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Oct 19 15:04:02 CEST 2017
From: Lokesh Vutla <lokeshvutla@ti.com>
Date: Mon, 27 Feb 2017 14:28:12 -0800
Subject: initramfs: finish fput() before accessing any binary from initramfs

From: Lokesh Vutla <lokeshvutla@ti.com>


[ Upstream commit 08865514805d2de8e7002fa8149c5de3e391f412 ]

Commit 4a9d4b024a31 ("switch fput to task_work_add") implements a
schedule_work() for completing fput(), but did not guarantee calling
__fput() after unpacking initramfs.  Because of this, there is a
possibility that during boot a driver can see ETXTBSY when it tries to
load a binary from initramfs as fput() is still pending on that binary.

This patch makes sure that fput() is completed after unpacking initramfs
and removes the call to flush_delayed_fput() in kernel_init() which
happens very late after unpacking initramfs.

Link: http://lkml.kernel.org/r/20170201140540.22051-1-lokeshvutla@ti.com
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reported-by: Murali Karicheri <m-karicheri2@ti.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tero Kristo <t-kristo@ti.com>
Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Nishanth Menon <nm@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 init/initramfs.c |    2 ++
 init/main.c      |    3 ---
 2 files changed, 2 insertions(+), 3 deletions(-)

--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -18,6 +18,7 @@
 #include <linux/dirent.h>
 #include <linux/syscalls.h>
 #include <linux/utime.h>
+#include <linux/file.h>
 
 static ssize_t __init xwrite(int fd, const char *p, size_t count)
 {
@@ -647,6 +648,7 @@ static int __init populate_rootfs(void)
 			printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
 		free_initrd();
 #endif
+		flush_delayed_fput();
 		/*
 		 * Try loading default modules from initramfs.  This gives
 		 * us a chance to load before device_initcalls.
--- a/init/main.c
+++ b/init/main.c
@@ -70,7 +70,6 @@
 #include <linux/shmem_fs.h>
 #include <linux/slab.h>
 #include <linux/perf_event.h>
-#include <linux/file.h>
 #include <linux/ptrace.h>
 #include <linux/blkdev.h>
 #include <linux/elevator.h>
@@ -947,8 +946,6 @@ static int __ref kernel_init(void *unuse
 	system_state = SYSTEM_RUNNING;
 	numa_default_policy();
 
-	flush_delayed_fput();
-
 	rcu_end_inkernel_boot();
 
 	if (ramdisk_execute_command) {


Patches currently in stable-queue which might be from lokeshvutla@ti.com are

queue-4.9/initramfs-finish-fput-before-accessing-any-binary-from-initramfs.patch