Commit-ID: abcdc1c694fa4055323cbec1cde4c2cb6b68398c
Gitweb: http://git.kernel.org/tip/abcdc1c694fa4055323cbec1cde4c2cb6b68398c
Author: Dave Hansen <[email protected]>
AuthorDate: Tue, 22 Dec 2015 14:52:39 -0800
Committer: Ingo Molnar <[email protected]>
CommitDate: Wed, 3 Feb 2016 12:03:16 +0100
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 <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/lib/cmdline.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/arch/x86/lib/cmdline.c b/arch/x86/lib/cmdline.c
index 49548be..ff8d1be 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)
