linux-kernel - [PATCH v3 1/3] Revert "kernel/reboot.c: convert simple

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Date:   Tue,  3 Nov 2020 22:40:23 +0100
From:   Matteo Croce <mcroce@...ux.microsoft.com>
To:     linux-kernel@...r.kernel.org
Cc:     Guenter Roeck <linux@...ck-us.net>, Petr Mladek <pmladek@...e.com>,
        Arnd Bergmann <arnd@...db.de>, Mike Rapoport <rppt@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Robin Holt <robinmholt@...il.com>,
        Fabian Frederick <fabf@...net.be>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH v3 1/3] Revert "kernel/reboot.c: convert simple_strtoul to kstrtoint"

From: Matteo Croce <mcroce@...rosoft.com>

This reverts commit 616feab753972b9751308f3cd2a68fc57eae8edb.

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")
Cc: stable@...r.kernel.org
Signed-off-by: Matteo Croce <mcroce@...rosoft.com>
---
 kernel/reboot.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/kernel/reboot.c b/kernel/reboot.c
index e7b78d5ae1ab..8fbba433725e 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -551,22 +551,15 @@ 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
 				*mode = REBOOT_SOFT;
 			break;
-		}
+
 		case 'g':
 			*mode = REBOOT_GPIO;
 			break;
-- 
2.28.0