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Revert "kernel/reboot.c: convert simple_strtoul to kstrtoint"

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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 616feab753.

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: 616feab753 ("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>
This commit is contained in:
Matteo Croce 2020-11-13 22:52:02 -08:00 committed by Linus Torvalds
parent 3347acc6fc
commit 8b92c4ff44
1 changed files with 7 additions and 14 deletions
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21
kernel/reboot.c
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@ -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;