linux-kernel - [PATCH 1/3] mm: move argument checkers of mmap

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Date:   Sun, 11 Dec 2016 18:26:40 +0530
From:   Yury Norov <ynorov@...iumnetworks.com>
To:     unlisted-recipients:; (no To-header on input)
CC:     Yury Norov <ynorov@...iumnetworks.com>,
        Arnd Bergmann <arnd@...db.de>,
        "Dr. Philipp Tomsich" <philipp.tomsich@...obroma-systems.com>,
        Catalin Marinas <catalin.marinas@....com>,
        <libc-alpha@...rceware.org>, <linux-arch@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, <szabolcs.nagy@....com>,
        <heiko.carstens@...ibm.com>, <cmetcalf@...hip.com>,
        "Joseph S. Myers" <joseph@...esourcery.com>,
        <zhouchengming1@...wei.com>,
        "Kapoor, Prasun" <Prasun.Kapoor@...iumnetworks.com>,
        Alexander Graf <agraf@...e.de>, <geert@...ux-m68k.org>,
        <kilobyte@...band.pl>, <manuel.montezelo@...il.com>,
        Andrew Pinski <pinskia@...il.com>, <linyongting@...wei.com>,
        Alexey Klimov <klimov.linux@...il.com>, <broonie@...nel.org>,
        "Zhangjian (Bamvor)" <bamvor.zhangjian@...wei.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Maxim Kuvyrkov <maxim.kuvyrkov@...aro.org>,
        Nathan Lynch <Nathan_Lynch@...tor.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        <davem@...emloft.net>, <christoph.muellner@...obroma-systems.com>
Subject: [PATCH 1/3] mm: move argument checkers of mmap_pgoff() to separated routine

Signed-off-by: Yury Norov <ynorov@...iumnetworks.com>
---
 mm/mmap.c | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 1af87c1..fc1c943 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1455,12 +1455,12 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 	return addr;
 }
 
-SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
-		unsigned long, prot, unsigned long, flags,
-		unsigned long, fd, unsigned long, pgoff)
+static int mmap_pgoff_prepare(struct file **f, unsigned long *l,
+		unsigned long *fl, unsigned long fd)
 {
-	struct file *file = NULL;
-	unsigned long retval;
+	struct file *file = *f;
+	unsigned long flags = *fl;
+	unsigned long len = *l;
 
 	if (!(flags & MAP_ANONYMOUS)) {
 		audit_mmap_fd(fd, flags);
@@ -1469,9 +1469,10 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
 			return -EBADF;
 		if (is_file_hugepages(file))
 			len = ALIGN(len, huge_page_size(hstate_file(file)));
-		retval = -EINVAL;
-		if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
-			goto out_fput;
+		if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) {
+			fput(file);
+			return -EINVAL;
+		}
 	} else if (flags & MAP_HUGETLB) {
 		struct user_struct *user = NULL;
 		struct hstate *hs;
@@ -1497,8 +1498,23 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
 
 	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
 
+	*f = file;
+	*l = len;
+	*fl = flags;
+	return 0;
+}
+
+SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
+		unsigned long, prot, unsigned long, flags,
+		unsigned long, fd, unsigned long, pgoff)
+{
+	struct file *file = NULL;
+	unsigned long retval;
+	int err = mmap_pgoff_prepare(&file, &len, &flags, fd);
+	if (err)
+		return err;
+
 	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
-out_fput:
 	if (file)
 		fput(file);
 	return retval;
-- 
2.7.4