[62/67] lib: make bitmap_parse_user a wrapper on bitmap_parse

Commit Message

Andrew Morton Feb. 4, 2020, 1:37 a.m. UTC

From: Yury Norov <[e-mail]>
Subject: lib: make bitmap_parse_user a wrapper on bitmap_parse

Currently we parse user data byte after byte which leads to
overcomplicating of parsing algorithm.  There are no performance critical
users of bitmap_parse_user(), and so we can duplicate user data to kernel
buffer and simply call bitmap_parselist().  This rework lets us unify and
simplify bitmap_parse() and bitmap_parse_user(), which is done in the
following patch.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Yury Norov <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Cc: Amritha Nambiar <[e-mail]>
Cc: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Chris Wilson <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Miklos Szeredi <[e-mail]>
Cc: Rasmus Villemoes <[e-mail]>
Cc: Steffen Klassert <[e-mail]>
Cc: "Tobin C . Harding" <[e-mail]>
Cc: Vineet Gupta <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Willem de Bruijn <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 lib/bitmap.c |   20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

Patch

--- a/lib/bitmap.c~lib-make-bitmap_parse_user-a-wrapper-on-bitmap_parse
+++ a/lib/bitmap.c
@@ -530,22 +530,22 @@  EXPORT_SYMBOL(__bitmap_parse);
  *    then it must be terminated with a \0.
  * @maskp: pointer to bitmap array that will contain result.
  * @nmaskbits: size of bitmap, in bits.
- *
- * Wrapper for __bitmap_parse(), providing it with user buffer.
- *
- * We cannot have this as an inline function in bitmap.h because it needs
- * linux/uaccess.h to get the access_ok() declaration and this causes
- * cyclic dependencies.
  */
 int bitmap_parse_user(const char __user *ubuf,
 			unsigned int ulen, unsigned long *maskp,
 			int nmaskbits)
 {
-	if (!access_ok(ubuf, ulen))
-		return -EFAULT;
-	return __bitmap_parse((const char __force *)ubuf,
-				ulen, 1, maskp, nmaskbits);
+	char *buf;
+	int ret;
 
+	buf = memdup_user_nul(ubuf, ulen);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	ret = bitmap_parse(buf, ulen, maskp, nmaskbits);
+
+	kfree(buf);
+	return ret;
 }
 EXPORT_SYMBOL(bitmap_parse_user);