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authorDave Hansen <dave.hansen@linux.intel.com>2015-12-23 01:52:39 +0300
committerIngo Molnar <mingo@kernel.org>2016-02-03 14:03:16 +0300
commitabcdc1c694fa4055323cbec1cde4c2cb6b68398c (patch)
tree8a01abcf694414fc8847903dd01b98bb5eed67df /arch/x86/lib
parent02afeaae9843733a39cd9b11053748b2d1dc5ae7 (diff)
downloadlinux-abcdc1c694fa4055323cbec1cde4c2cb6b68398c.tar.xz
x86/boot: Fix early command-line parsing when partial word matches
cmdline_find_option_bool() keeps track of position in two strings: 1. the command-line 2. the option we are searchign for in the command-line We plow through each character in the command-line one at a time, always moving forward. We move forward in the option ('opptr') when we match characters in 'cmdline'. We reset the 'opptr' only when we go in to the 'st_wordstart' state. But, if we fail to match an option because we see a space (state=st_wordcmp, *opptr='\0',c=' '), we set state='st_wordskip' and 'break', moving to the next character. But, that move to the next character is the one *after* the ' '. This means that we will miss a 'st_wordstart' state. For instance, if we have cmdline = "foo fool"; and are searching for "fool", we have: "fool" opptr = ----^ "foo fool" c = --------^ We see that 'l' != ' ', set state=st_wordskip, break, and then move 'c', so: "foo fool" c = ---------^ and are still in state=st_wordskip. We will stay in wordskip until we have skipped "fool", thus missing the option we were looking for. This *only* happens when you have a partially- matching word followed by a matching one. To fix this, we always fall *into* the 'st_wordskip' state when we set it. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: fenghua.yu@intel.com Cc: yu-cheng.yu@intel.com Link: http://lkml.kernel.org/r/20151222225239.8E1DCA58@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/lib')
-rw-r--r--arch/x86/lib/cmdline.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/arch/x86/lib/cmdline.c b/arch/x86/lib/cmdline.c
index 49548bed2301..ff8d1beead6c 100644
--- a/arch/x86/lib/cmdline.c
+++ b/arch/x86/lib/cmdline.c
@@ -72,18 +72,26 @@ int cmdline_find_option_bool(const char *cmdline, const char *option)
*/
if (!c || myisspace(c))
return wstart;
- else
- state = st_wordskip;
+ /*
+ * We hit the end of the option, but _not_
+ * the end of a word on the cmdline. Not
+ * a match.
+ */
} else if (!c) {
/*
* Hit the NULL terminator on the end of
* cmdline.
*/
return 0;
- } else if (c != *opptr++) {
- state = st_wordskip;
+ } else if (c == *opptr++) {
+ /*
+ * We are currently matching, so continue
+ * to the next character on the cmdline.
+ */
+ break;
}
- break;
+ state = st_wordskip;
+ /* fall through */
case st_wordskip:
if (!c)