[PATCH 4.19] Revert "initramfs: free initrd memory if opening /initrd.image fails"

[Stephen Boyd]

This reverts commit 25511676362d8f7d4b8805730a3d29484ceab1ec in the 4.19
stable trees. From what I can tell this commit doesn't do anything to
improve the situation, mostly just reordering code to call free_initrd()
from one place instead of many. In doing that, it causes free_initrd()
to be called even in the case when there isn't an initrd present. That
leads to virtual memory bugs that manifest on arm64 devices.

The fix has been merged upstream in commit 5d59aa8f9ce9 ("initramfs:
don't free a non-existent initrd"), but backporting that here is more
complicated because the patch is stacked upon this patch being reverted
along with more patches that rewrites the logic in this area.

Let's just revert the patch from the stable tree instead of trying to
backport a collection of fixes to get the final fix from upstream.

Cc: Sasha Levin <sashal@xxxxxxxxxx>
Cc: Steven Price <steven.price@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---

This patch is for 4.19 stable series.

 init/initramfs.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/init/initramfs.c b/init/initramfs.c
index cd5fb00fcb54..f6f4a1e4cd54 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -612,12 +612,13 @@ 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)
+		if (!err) {
+			free_initrd();
 			goto done;
-
-		clean_rootfs();
-		unpack_to_rootfs(__initramfs_start, __initramfs_size);
-
+		} else {
+			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",
@@ -631,6 +632,7 @@ static int __init populate_rootfs(void)
 				       written, initrd_end - initrd_start);
 
 			ksys_close(fd);
+			free_initrd();
 		}
 	done:
 		/* empty statement */;
@@ -640,9 +642,9 @@ 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
-- 
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