From: Steven Price <steven.price@arm.com>
Date: Fri, 17 May 2019 21:31:47 +0000 (-0700)
Subject: initramfs: don't free a non-existent initrd
X-Git-Tag: Ubuntu-4.15.0-67.76~130
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=ddd4dbf420c8c023648495250d093c06633ea839;p=mirror_ubuntu-bionic-kernel.git

initramfs: don't free a non-existent initrd

BugLink: https://bugs.launchpad.net/bugs/1847155

[ Upstream commit 5d59aa8f9ce972b472201aed86e904bb75879ff0 ]

Since commit 54c7a8916a88 ("initramfs: free initrd memory if opening
/initrd.image fails"), the kernel has unconditionally attempted to free
the initrd even if it doesn't exist.

In the non-existent case this causes a boot-time splat if
CONFIG_DEBUG_VIRTUAL is enabled due to a call to virt_to_phys() with a
NULL address.

Instead we should check that the initrd actually exists and only attempt
to free it if it does.

Link: http://lkml.kernel.org/r/20190516143125.48948-1-steven.price@arm.com
Fixes: 54c7a8916a88 ("initramfs: free initrd memory if opening /initrd.image fails")
Signed-off-by: Steven Price <steven.price@arm.com>
Reported-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
---

diff --git a/init/initramfs.c b/init/initramfs.c
index 4be1b65b0676..ffcccf01e77e 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -532,7 +532,7 @@ static void __init free_initrd(void)
 	unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
 	unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
 #endif
-	if (do_retain_initrd)
+	if (do_retain_initrd || !initrd_start)
 		goto skip;
 
 #ifdef CONFIG_KEXEC_CORE