lib/bitmap.c: bitmap_parselist can accept string with whitespaces on head or tail

In __bitmap_parselist we can accept whitespaces on head or tail during
every parsing procedure.  If input has valid ranges, there is no reason to
reject the user.

For example, bitmap_parselist(" 1-3, 5, ", &mask, nmaskbits).  After
separating the string, we get " 1-3", " 5", and " ".  It's possible and
reasonable to accept such string as long as the parsing result is correct.

Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/bitmap.c b/lib/bitmap.c
index f549176..8148143 100644 (file)
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -506,7 +506,7 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen,
                int nmaskbits)
 {
        unsigned a, b;
-       int c, old_c, totaldigits;
+       int c, old_c, totaldigits, ndigits;
        const char __user __force *ubuf = (const char __user __force *)buf;
        int at_start, in_range;
 
@@ -516,6 +516,7 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen,
                at_start = 1;
                in_range = 0;
                a = b = 0;
+               ndigits = totaldigits;
 
                /* Get the next cpu# or a range of cpu#'s */
                while (buflen) {
@@ -529,17 +530,20 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen,
                        if (isspace(c))
                                continue;
 
-                       /*
-                        * If the last character was a space and the current
-                        * character isn't '\0', we've got embedded whitespace.
-                        * This is a no-no, so throw an error.
-                        */
-                       if (totaldigits && c && isspace(old_c))
-                               return -EINVAL;
-
                        /* A '\0' or a ',' signal the end of a cpu# or range */
                        if (c == '\0' || c == ',')
                                break;
+                       /*
+                       * whitespaces between digits are not allowed,
+                       * but it's ok if whitespaces are on head or tail.
+                       * when old_c is whilespace,
+                       * if totaldigits == ndigits, whitespace is on head.
+                       * if whitespace is on tail, it should not run here.
+                       * as c was ',' or '\0',
+                       * the last code line has broken the current loop.
+                       */
+                       if ((totaldigits != ndigits) && isspace(old_c))
+                               return -EINVAL;
 
                        if (c == '-') {
                                if (at_start || in_range)
@@ -559,6 +563,8 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen,
                        at_start = 0;
                        totaldigits++;
                }
+               if (ndigits == totaldigits)
+                       continue;
                /* if no digit is after '-', it's wrong*/
                if (at_start && in_range)
                        return -EINVAL;
@@ -566,11 +572,9 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen,
                        return -EINVAL;
                if (b >= nmaskbits)
                        return -ERANGE;
-               if (!at_start) {
-                       while (a <= b) {
-                               set_bit(a, maskp);
-                               a++;
-                       }
+               while (a <= b) {
+                       set_bit(a, maskp);
+                       a++;
                }
        } while (buflen && c == ',');
        return 0;