[RFC PATCH 6/8] sg_read(): get rid of access_ok()/__copy_..._user()

From: Al Viro
Date: Thu Oct 17 2019 - 15:39:49 EST


From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

Use copy_..._user() instead, both in sg_read() and in sg_read_oxfer().
And don't open-code memdup_user()...

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
drivers/scsi/sg.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 3702f66493f7..9f6534a025cd 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -429,16 +429,10 @@ sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
"sg_read: count=%d\n", (int) count));

- if (!access_ok(buf, count))
- return -EFAULT;
if (sfp->force_packid && (count >= SZ_SG_HEADER)) {
- old_hdr = kmalloc(SZ_SG_HEADER, GFP_KERNEL);
- if (!old_hdr)
- return -ENOMEM;
- if (__copy_from_user(old_hdr, buf, SZ_SG_HEADER)) {
- retval = -EFAULT;
- goto free_old_hdr;
- }
+ old_hdr = memdup_user(buf, SZ_SG_HEADER);
+ if (IS_ERR(old_hdr))
+ return PTR_ERR(old_hdr);
if (old_hdr->reply_len < 0) {
if (count >= SZ_SG_IO_HDR) {
sg_io_hdr_t __user *p = (void __user *)buf;
@@ -529,7 +523,7 @@ sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)

/* Now copy the result back to the user buffer. */
if (count >= SZ_SG_HEADER) {
- if (__copy_to_user(buf, old_hdr, SZ_SG_HEADER)) {
+ if (copy_to_user(buf, old_hdr, SZ_SG_HEADER)) {
retval = -EFAULT;
goto free_old_hdr;
}
@@ -1960,12 +1954,12 @@ sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer)
num = 1 << (PAGE_SHIFT + schp->page_order);
for (k = 0; k < schp->k_use_sg && schp->pages[k]; k++) {
if (num > num_read_xfer) {
- if (__copy_to_user(outp, page_address(schp->pages[k]),
+ if (copy_to_user(outp, page_address(schp->pages[k]),
num_read_xfer))
return -EFAULT;
break;
} else {
- if (__copy_to_user(outp, page_address(schp->pages[k]),
+ if (copy_to_user(outp, page_address(schp->pages[k]),
num))
return -EFAULT;
num_read_xfer -= num;
--
2.11.0