diff mbox series

[08/14] Revert "kernel/reboot.c: convert simple_strtoul to kstrtoint"

Message ID 20201114065202.FWrl0Eulf%akpm@linux-foundation.org (mailing list archive)
State New
Headers show
Series [01/14] mm/compaction: count pages and stop correctly during page isolation | expand

Commit Message

Andrew Morton Nov. 14, 2020, 6:52 a.m. UTC
From: Matteo Croce <mcroce@microsoft.com>
Subject: Revert "kernel/reboot.c: convert simple_strtoul to kstrtoint"

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.

Link: https://lkml.kernel.org/r/20201103214025.116799-2-mcroce@linux.microsoft.com
Fixes: 616feab75397 ("kernel/reboot.c: convert simple_strtoul to kstrtoint")
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

 kernel/reboot.c |   21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)
diff mbox series


--- a/kernel/reboot.c~revert-kernel-rebootc-convert-simple_strtoul-to-kstrtoint
+++ a/kernel/reboot.c
@@ -551,22 +551,15 @@  static int __init reboot_setup(char *str
 		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;
-		}
 		case 'g':
 			*mode = REBOOT_GPIO;