[PATCH 3/5] x86: simplify early command line parsing

Dave Hansen
2015-12-22T22:53:16Z

From: Dave Hansen <dave.hansen@linux.intel.com>

__cmdline_find_option_bool() tries to account for both
NULL-terminated and non-NULL-terminated strings. It keeps 'pos'
to look for the end of the buffer and also looks for '!c' in a
bunch of places to look for NULL termination.

But, it also calls strlen(). You can't call strlen on a
non-NULL-terminated string.

If !strlen(cmdline), then cmdline[0]=='\0'. In that case, we
will go in to the while() loop, set c='\0', hit st_wordstart,
notice !c, and will immediately return 0.

So, remove the strlen(). It is unnecessary and unsafe.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org
Cc: fenghua.yu@intel.com
Cc: yu-cheng.yu@intel.com
---

b/arch/x86/lib/cmdline.c | 3 ---
1 file changed, 3 deletions(-)

diff -puN arch/x86/lib/cmdline.c~x86-early-command-line-non-term arch/x86/lib/cmdline.c
--- a/arch/x86/lib/cmdline.c~x86-early-command-line-non-term 2015-12-22 11:56:59.454186167 -0800
+++ b/arch/x86/lib/cmdline.c 2015-12-22 11:56:59.457186302 -0800
@@ -39,9 +39,6 @@ int cmdline_find_option_bool(const char
if (!cmdline)
return -1; /* No command line */

- if (!strlen(cmdline))
- return 0;
-
/*
* This 'pos' check ensures we do not overrun
* a non-NULL-terminated 'cmdline'
_