This is a note to let you know that I've just added the patch titled

x86/boot: Add early cmdline parsing for options with arguments

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-boot-add-early-cmdline-parsing-for-options-with-arguments.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From e505371dd83963caae1a37ead9524e8d997341be Mon Sep 17 00:00:00 2001

From: Tom Lendacky thomas.lendacky@amd.com Date: Mon, 17 Jul 2017 16:10:33 -0500 Subject: x86/boot: Add early cmdline parsing for options with arguments MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

From: Tom Lendacky thomas.lendacky@amd.com

commit e505371dd83963caae1a37ead9524e8d997341be upstream.

Add a cmdline_find_option() function to look for cmdline options that take arguments. The argument is returned in a supplied buffer and the argument length (regardless of whether it fits in the supplied buffer) is returned, with -1 indicating not found.

Signed-off-by: Tom Lendacky thomas.lendacky@amd.com Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: Alexander Potapenko glider@google.com Cc: Andrey Ryabinin aryabinin@virtuozzo.com Cc: Andy Lutomirski luto@kernel.org Cc: Arnd Bergmann arnd@arndb.de Cc: Borislav Petkov bp@alien8.de Cc: Brijesh Singh brijesh.singh@amd.com Cc: Dave Young dyoung@redhat.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Jonathan Corbet corbet@lwn.net Cc: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Cc: Larry Woodman lwoodman@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Matt Fleming matt@codeblueprint.co.uk Cc: Michael S. Tsirkin mst@redhat.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Radim Krčmář rkrcmar@redhat.com Cc: Rik van Riel riel@redhat.com Cc: Toshimitsu Kani toshi.kani@hpe.com Cc: kasan-dev@googlegroups.com Cc: kvm@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-efi@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/36b5f97492a9745dce27682305f990fc20e5cf8a.1500319216... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/include/asm/cmdline.h | 2 arch/x86/lib/cmdline.c | 105 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 107 insertions(+)

--- a/arch/x86/include/asm/cmdline.h +++ b/arch/x86/include/asm/cmdline.h @@ -2,5 +2,7 @@ #define _ASM_X86_CMDLINE_H

int cmdline_find_option_bool(const char *cmdline_ptr, const char *option); +int cmdline_find_option(const char *cmdline_ptr, const char *option, + char *buffer, int bufsize);

#endif /* _ASM_X86_CMDLINE_H */ --- a/arch/x86/lib/cmdline.c +++ b/arch/x86/lib/cmdline.c @@ -104,7 +104,112 @@ __cmdline_find_option_bool(const char *c return 0; /* Buffer overrun */ }

+/* + * Find a non-boolean option (i.e. option=argument). In accordance with + * standard Linux practice, if this option is repeated, this returns the + * last instance on the command line. + * + * @cmdline: the cmdline string + * @max_cmdline_size: the maximum size of cmdline + * @option: option string to look for + * @buffer: memory buffer to return the option argument + * @bufsize: size of the supplied memory buffer + * + * Returns the length of the argument (regardless of if it was + * truncated to fit in the buffer), or -1 on not found. + */ +static int +__cmdline_find_option(const char *cmdline, int max_cmdline_size, + const char *option, char *buffer, int bufsize) +{ + char c; + int pos = 0, len = -1; + const char *opptr = NULL; + char *bufptr = buffer; + enum { + st_wordstart = 0, /* Start of word/after whitespace */ + st_wordcmp, /* Comparing this word */ + st_wordskip, /* Miscompare, skip */ + st_bufcpy, /* Copying this to buffer */ + } state = st_wordstart; + + if (!cmdline) + return -1; /* No command line */ + + /* + * This 'pos' check ensures we do not overrun + * a non-NULL-terminated 'cmdline' + */ + while (pos++ < max_cmdline_size) { + c = *(char *)cmdline++; + if (!c) + break; + + switch (state) { + case st_wordstart: + if (myisspace(c)) + break; + + state = st_wordcmp; + opptr = option; + /* fall through */ + + case st_wordcmp: + if ((c == '=') && !*opptr) { + /* + * We matched all the way to the end of the + * option we were looking for, prepare to + * copy the argument. + */ + len = 0; + bufptr = buffer; + state = st_bufcpy; + break; + } else if (c == *opptr++) { + /* + * We are currently matching, so continue + * to the next character on the cmdline. + */ + break; + } + state = st_wordskip; + /* fall through */ + + case st_wordskip: + if (myisspace(c)) + state = st_wordstart; + break; + + case st_bufcpy: + if (myisspace(c)) { + state = st_wordstart; + } else { + /* + * Increment len, but don't overrun the + * supplied buffer and leave room for the + * NULL terminator. + */ + if (++len < bufsize) + *bufptr++ = c; + } + break; + } + } + + if (bufsize) + *bufptr = '\0'; + + return len; +} + int cmdline_find_option_bool(const char *cmdline, const char *option) { return __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option); } + +int cmdline_find_option(const char *cmdline, const char *option, char *buffer, + int bufsize) +{ + return __cmdline_find_option(cmdline, COMMAND_LINE_SIZE, option, + buffer, bufsize); +}

Patches currently in stable-queue which might be from thomas.lendacky@amd.com are

queue-4.9/x86-boot-add-early-cmdline-parsing-for-options-with-arguments.patch