[3.16.y-ckt stable] Patch "param: fix crash on bad kernel arguments" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    param: fix crash on bad kernel arguments

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt2.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 9a7ee8dd114fba47ccc6fc209571283afd749f76 Mon Sep 17 00:00:00 2001
From: Daniel Thompson <daniel.thompson at linaro.org>
Date: Tue, 11 Nov 2014 16:29:46 +1030
Subject: param: fix crash on bad kernel arguments

commit 3438cf549d2f3ee8e52c82acc8e2a9710ac21a5b upstream.

Currently if the user passes an invalid value on the kernel command line
then the kernel will crash during argument parsing. On most systems this
is very hard to debug because the console hasn't been initialized yet.

This is a regression due to commit 51e158c12aca ("param: hand arguments
after -- straight to init") which, in response to the systemd debug
controversy, made it possible to explicitly pass arguments to init. To
achieve this parse_args() was extended from simply returning an error
code to returning a pointer. Regretably the new init args logic does not
perform a proper validity check on the pointer resulting in a crash.

This patch fixes the validity check. Should the check fail then no arguments
will be passed to init. This is reasonable and matches how the kernel treats
its own arguments (i.e. no error recovery).

Signed-off-by: Daniel Thompson <daniel.thompson at linaro.org>
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 init/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/init/main.c b/init/main.c
index e8ae1fef0908..ed5f48edc7a8 100644
--- a/init/main.c
+++ b/init/main.c
@@ -544,7 +544,7 @@ asmlinkage __visible void __init start_kernel(void)
 				  static_command_line, __start___param,
 				  __stop___param - __start___param,
 				  -1, -1, &unknown_bootoption);
-	if (after_dashes)
+	if (!IS_ERR_OR_NULL(after_dashes))
 		parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
 			   set_init_arg);

--
2.1.0