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>

1 files changed, 18 insertions, 14 deletions

diff --git a/lib/bitmap.c b/lib/bitmap.c
index f549176e9250..814814397cce 100644
--- 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;