[PATCH 4/7] lib: make bitmap_parse_user a wrapper on bitmap_parse

From: Yury Norov <yury.norov@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	"David S . Miller" <davem@davemloft.net>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Amritha Nambiar <amritha.nambiar@intel.com>,
	Willem de Bruijn <willemb@google.com>,
	Kees Cook <keescook@chromium.org>,
	Matthew Wilcox <willy@infradead.org>,
	"Tobin C . Harding" <tobin@kernel.org>,
	Will Deacon <will.deacon@arm.com>,
	Miklos Szeredi <mszeredi@redhat.com>,
	Vineet Gupta <vineet.gupta1@synopsys.com>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	linux-kernel@vger.kernel.org
Cc: Yury Norov <yury.norov@gmail.com>, Jens Axboe <axboe@kernel.dk>,
	Steffen Klassert <steffen.klassert@secunet.com>
Subject: [PATCH 4/7] lib: make bitmap_parse_user a wrapper on bitmap_parse
Date: Wed,  1 Jan 2020 20:30:28 -0800	[thread overview]
Message-ID: <20200102043031.30357-5-yury.norov@gmail.com> (raw)
In-Reply-To: <20200102043031.30357-1-yury.norov@gmail.com>

From Yury Norov <yury.norov@gmail.com>

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.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 lib/bitmap.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 4250519d7d1c5..b9ac2d42b99e1 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -464,22 +464,22 @@ 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);
 
-- 
2.20.1

