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x86/boot: Simplify early command line parsing

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__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>
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/20151222225241.15365E43@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Dave Hansen 2015-12-22 14:52:41 -08:00 committed by Ingo Molnar
parent abcdc1c694
commit 4de07ea481
1 changed files with 0 additions and 3 deletions
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3
arch/x86/lib/cmdline.c
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@ -39,9 +39,6 @@ int cmdline_find_option_bool(const char *cmdline, const char *option)
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'