mtd: Fix warning in access_ok() parameter passing

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=f62cde49f9f02d6c205ab310b8fd4a29ddc49329
Commit:     f62cde49f9f02d6c205ab310b8fd4a29ddc49329
Parent:     f306e8c3b667632952f1a4a74ffb910bbc06255f
Author:     Geert Uytterhoeven <geert at linux-m68k.org>
AuthorDate: Thu May 1 20:40:54 2014 +0200
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Tue May 20 16:35:29 2014 -0700

    mtd: Fix warning in access_ok() parameter passing
    
    On m68k, where access_ok() doesn't cast the address parameter:
    
    drivers/mtd/mtdchar.c: In function 'mtdchar_write_ioctl':
    drivers/mtd/mtdchar.c:575:4: warning: passing argument 2 of 'access_ok' makes pointer from integer without a cast [enabled by default]
    arch/m68k/include/asm/uaccess_mm.h:17:90: note: expected 'const void *' but argument is of type '__u64'
    drivers/mtd/mtdchar.c:576:4: warning: passing argument 2 of 'access_ok' makes pointer from integer without a cast [enabled by default]
    arch/m68k/include/asm/uaccess_mm.h:17:90: note: expected 'const void *' but argument is of type '__u64'
    
    The address parameter of access_ok() is really a userspace pointer.
    On most architectures, access_ok() is a macro that casts the address
    parameter, hiding issues in its users.
    
    Move around and use the existing usr_data and usr_oob temporary variables
    to kill the warnings. Add a few "consts", and make more use of the
    temporaries while we're at it.
    
    Signed-off-by: Geert Uytterhoeven <geert at linux-m68k.org>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/mtdchar.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 7d4e7b9..a0f54e8 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -568,13 +568,18 @@ static int mtdchar_write_ioctl(struct mtd_info *mtd,
 {
 	struct mtd_write_req req;
 	struct mtd_oob_ops ops;
-	void __user *usr_data, *usr_oob;
+	const void __user *usr_data, *usr_oob;
 	int ret;
 
-	if (copy_from_user(&req, argp, sizeof(req)) ||
-			!access_ok(VERIFY_READ, req.usr_data, req.len) ||
-			!access_ok(VERIFY_READ, req.usr_oob, req.ooblen))
+	if (copy_from_user(&req, argp, sizeof(req)))
 		return -EFAULT;
+
+	usr_data = (const void __user *)(uintptr_t)req.usr_data;
+	usr_oob = (const void __user *)(uintptr_t)req.usr_oob;
+	if (!access_ok(VERIFY_READ, usr_data, req.len) ||
+	    !access_ok(VERIFY_READ, usr_oob, req.ooblen))
+		return -EFAULT;
+
 	if (!mtd->_write_oob)
 		return -EOPNOTSUPP;
 
@@ -583,10 +588,7 @@ static int mtdchar_write_ioctl(struct mtd_info *mtd,
 	ops.ooblen = (size_t)req.ooblen;
 	ops.ooboffs = 0;
 
-	usr_data = (void __user *)(uintptr_t)req.usr_data;
-	usr_oob = (void __user *)(uintptr_t)req.usr_oob;
-
-	if (req.usr_data) {
+	if (usr_data) {
 		ops.datbuf = memdup_user(usr_data, ops.len);
 		if (IS_ERR(ops.datbuf))
 			return PTR_ERR(ops.datbuf);
@@ -594,7 +596,7 @@ static int mtdchar_write_ioctl(struct mtd_info *mtd,
 		ops.datbuf = NULL;
 	}
 
-	if (req.usr_oob) {
+	if (usr_oob) {
 		ops.oobbuf = memdup_user(usr_oob, ops.ooblen);
 		if (IS_ERR(ops.oobbuf)) {
 			kfree(ops.datbuf);