1 files changed, 129 insertions, 10 deletions

diff --git a/arch/x86/lib/cmdline.c b/arch/x86/lib/cmdline.c
index 422db000d727..88ce150186c6 100644
--- a/arch/x86/lib/cmdline.c
+++ b/arch/x86/lib/cmdline.c
@@ -21,12 +21,14 @@ static inline int myisspace(u8 c)
  * @option: option string to look for
  *
  * Returns the position of that @option (starts counting with 1)
- * or 0 on not found.
+ * or 0 on not found.  @option will only be found if it is found
+ * as an entire word in @cmdline.  For instance, if @option="car"
+ * then a cmdline which contains "cart" will not match.
  */
 int cmdline_find_option_bool(const char *cmdline, const char *option)
 {
 	char c;
-	int len, pos = 0, wstart = 0;
+	int pos = 0, wstart = 0;
 	const char *opptr = NULL;
 	enum {
 		st_wordstart = 0,	/* Start of word/after whitespace */
@@ -37,11 +39,14 @@ int cmdline_find_option_bool(const char *cmdline, const char *option)
 	if (!cmdline)
 		return -1;      /* No command line */
 
-	len = min_t(int, strlen(cmdline), COMMAND_LINE_SIZE);
-	if (!len)
+	if (!strlen(cmdline))
 		return 0;
 
-	while (len--) {
+	/*
+	 * This 'pos' check ensures we do not overrun
+	 * a non-NULL-terminated 'cmdline'
+	 */
+	while (pos < COMMAND_LINE_SIZE) {
 		c = *(char *)cmdline++;
 		pos++;
 
@@ -58,17 +63,26 @@ int cmdline_find_option_bool(const char *cmdline, const char *option)
 			/* fall through */
 
 		case st_wordcmp:
-			if (!*opptr)
+			if (!*opptr) {
+				/*
+				 * We matched all the way to the end of the
+				 * option we were looking for.  If the
+				 * command-line has a space _or_ ends, then
+				 * we matched!
+				 */
 				if (!c || myisspace(c))
 					return wstart;
 				else
 					state = st_wordskip;
-			else if (!c)
+			} else if (!c) {
+				/*
+				 * Hit the NULL terminator on the end of
+				 * cmdline.
+				 */
 				return 0;
-			else if (c != *opptr++)
+			} else if (c != *opptr++) {
 				state = st_wordskip;
-			else if (!len)		/* last word and is matching */
-				return wstart;
+			}
 			break;
 
 		case st_wordskip:
@@ -82,3 +96,108 @@ int cmdline_find_option_bool(const char *cmdline, const char *option)
 
 	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(const char *cmdline, const char *option, char *buffer,
+			int bufsize)
+{
+	return __cmdline_find_option(cmdline, COMMAND_LINE_SIZE, option,
+				     buffer, bufsize);
+}