linux-kernel - [PATCH 4.11 092/114] initramfs: Always do fput() and load modules after rootfs populate

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Message-Id: <20170518103618.690080273@linuxfoundation.org>
Date:   Thu, 18 May 2017 12:46:42 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lokesh Vutla <lokeshvutla@...com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Stafford Horne <shorne@...il.com>
Subject: [PATCH 4.11 092/114] initramfs: Always do fput() and load modules after rootfs populate

4.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stafford Horne <shorne@...il.com>

commit 17a9be31747535184f2af156b1f080ec4c92a952 upstream.

In OpenRISC we do not have a bootloader passed initrd, but the built in
initramfs does contain the /init and other binaries, including modules.
The previous commit 08865514805d2 ("initramfs: finish fput() before
accessing any binary from initramfs") made a change to only call fput()
if the bootloader initrd was available, this caused intermittent crashes
for OpenRISC.

This patch changes the fput() to happen unconditionally if any rootfs is
loaded. Also, I added some comments to make it a bit more clear why we
call unpack_to_rootfs() multiple times.

Fixes: 08865514805d2 ("initramfs: finish fput() before accessing any binary from initramfs")
Cc: Lokesh Vutla <lokeshvutla@...com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Acked-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Stafford Horne <shorne@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 init/initramfs.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -608,9 +608,11 @@ static void __init clean_rootfs(void)
 
 static int __init populate_rootfs(void)
 {
+	/* Load the built in initramfs */
 	char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
 	if (err)
 		panic("%s", err); /* Failed to decompress INTERNAL initramfs */
+	/* If available load the bootloader supplied initrd */
 	if (initrd_start) {
 #ifdef CONFIG_BLK_DEV_RAM
 		int fd;
@@ -648,13 +650,14 @@ 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.
-		 */
-		load_default_modules();
 	}
+	flush_delayed_fput();
+	/*
+	 * Try loading default modules from initramfs.  This gives
+	 * us a chance to load before device_initcalls.
+	 */
+	load_default_modules();
+
 	return 0;
 }
 rootfs_initcall(populate_rootfs);