From 8b92c4ff4423aa9900cf838d3294fcade4dbda35 Mon Sep 17 00:00:00 2001

From: Matteo Croce <mcroce@microsoft.com>

Date: Fri, 13 Nov 2020 22:52:02 -0800

Subject: [PATCH] Revert "kernel/reboot.c: convert simple_strtoul to kstrtoint"

References: bsc#1179418

Git-commit: 8b92c4ff4423aa9900cf838d3294fcade4dbda35

Patch-mainline: v5.10-rc4

Patch series "fix parsing of reboot= cmdline", v3.

The parsing of the reboot= cmdline has two major errors:

 - a missing bound check can crash the system on reboot

 - parsing of the cpu number only works if specified last

Fix both.

This patch (of 2):

This reverts commit 616feab753972b97.

kstrtoint() and simple_strtoul() have a subtle difference which makes

them non interchangeable: if a non digit character is found amid the

parsing, the former will return an error, while the latter will just

stop parsing, e.g.  simple_strtoul("123xyx") = 123.

The kernel cmdline reboot= argument allows to specify the CPU used for

rebooting, with the syntax `s####` among the other flags, e.g.

"reboot=warm,s31,force", so if this flag is not the last given, it's

silently ignored as well as the subsequent ones.

Fixes: 616feab75397 ("kernel/reboot.c: convert simple_strtoul to kstrtoint")

Signed-off-by: Matteo Croce <mcroce@microsoft.com>

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Cc: Guenter Roeck <linux@roeck-us.net>

Cc: Petr Mladek <pmladek@suse.com>

Cc: Arnd Bergmann <arnd@arndb.de>

Cc: Mike Rapoport <rppt@kernel.org>

Cc: Kees Cook <keescook@chromium.org>

Cc: Pavel Tatashin <pasha.tatashin@soleen.com>

Cc: Robin Holt <robinmholt@gmail.com>

Cc: Fabian Frederick <fabf@skynet.be>

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Cc: <stable@vger.kernel.org>

Link: https://lkml.kernel.org/r/20201103214025.116799-2-mcroce@linux.microsoft.com

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Acked-by: Petr Mladek <pmladek@suse.com>

---

 kernel/reboot.c |   21 +++++++--------------

 1 file changed, 7 insertions(+), 14 deletions(-)

--- a/kernel/reboot.c

+++ b/kernel/reboot.c

@@ -512,22 +512,15 @@ static int __init reboot_setup(char *str

 			break;

 		case 's':

-		{

-			int rc;

-

-			if (isdigit(*(str+1))) {

-				rc = kstrtoint(str+1, 0, &reboot_cpu);

-				if (rc)

-					return rc;

-			} else if (str[1] == 'm' && str[2] == 'p' &&

-				   isdigit(*(str+3))) {

-				rc = kstrtoint(str+3, 0, &reboot_cpu);

-				if (rc)

-					return rc;

-			} else

+			if (isdigit(*(str+1)))

+				reboot_cpu = simple_strtoul(str+1, NULL, 0);

+			else if (str[1] == 'm' && str[2] == 'p' &&

+							isdigit(*(str+3)))

+				reboot_cpu = simple_strtoul(str+3, NULL, 0);

+			else

 				reboot_mode = REBOOT_SOFT;

 			break;

-		}

+

 		case 'g':

 			reboot_mode = REBOOT_GPIO;

 			break;