forked from luck/tmp_suning_uos_patched
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>
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@ -72,18 +72,26 @@ int cmdline_find_option_bool(const char *cmdline, const char *option)
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*/
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if (!c || myisspace(c))
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return wstart;
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else
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state = st_wordskip;
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/*
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* We hit the end of the option, but _not_
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* the end of a word on the cmdline. Not
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* a match.
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*/
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} else if (!c) {
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/*
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* Hit the NULL terminator on the end of
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* cmdline.
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*/
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return 0;
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} else if (c != *opptr++) {
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state = st_wordskip;
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}
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} else if (c == *opptr++) {
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/*
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* We are currently matching, so continue
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* to the next character on the cmdline.
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*/
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break;
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}
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state = st_wordskip;
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/* fall through */
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case st_wordskip:
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if (!c)
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