initramfs: free initrd memory if opening /initrd.image fails

[ Upstream commit 54c7a8916a887f357088f99e9c3a7720cd57d2c8 ]

Patch series "initramfs tidyups".

I've spent some time chasing down behavior in initramfs and found
plenty of opportunity to improve the code.  A first stab on that is
contained in this series.

This patch (of 7):

We free the initrd memory for all successful or error cases except for the
case where opening /initrd.image fails, which looks like an oversight.

Steven said:

: This also changes the behaviour when CONFIG_INITRAMFS_FORCE is enabled
: - specifically it means that the initrd is freed (previously it was
: ignored and never freed).  But that seems like reasonable behaviour and
: the previous behaviour looks like another oversight.

Link: http://lkml.kernel.org/r/20190213174621.29297-3-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Steven Price <steven.price@arm.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Cc: Geert Uytterhoeven <geert@linux-m68k.org>	[m68k]
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

init/initramfs.c

@@ -612,13 +612,12 @@ static int __init populate_rootfs(void)
 		printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
 		err = unpack_to_rootfs((char *)initrd_start,
 			initrd_end - initrd_start);
-		if (!err) {
-			free_initrd();
+		if (!err)
 			goto done;
-		} else {
-			clean_rootfs();
-			unpack_to_rootfs(__initramfs_start, __initramfs_size);
-		}
+
+		clean_rootfs();
+		unpack_to_rootfs(__initramfs_start, __initramfs_size);
+
 		printk(KERN_INFO "rootfs image is not initramfs (%s)"
 				"; looks like an initrd\n", err);
 		fd = ksys_open("/initrd.image",
@@ -632,7 +631,6 @@ static int __init populate_rootfs(void)
 				       written, initrd_end - initrd_start);
 
 			ksys_close(fd);
-			free_initrd();
 		}
 	done:
 		/* empty statement */;
@@ -642,9 +640,9 @@ static int __init populate_rootfs(void)
 			initrd_end - initrd_start);
 		if (err)
 			printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
-		free_initrd();
 #endif
 	}
+	free_initrd();
 	flush_delayed_fput();
 	/*
 	 * Try loading default modules from initramfs.  This gives