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Subject[RFC PATCH 4/8] sg_read(): simplify reading ->pack_id of userland sg_io_hdr_t
Date
From: Al Viro <viro@zeniv.linux.org.uk>

We don't need to allocate a temporary buffer and read the entire
structure in it, only to fetch a single field and free what we'd
allocated. Just use get_user() and be done with it...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
drivers/scsi/sg.c | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 4c62237cdf37..2d30e89075e9 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -441,17 +441,8 @@ sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
}
if (old_hdr->reply_len < 0) {
if (count >= SZ_SG_IO_HDR) {
- sg_io_hdr_t *new_hdr;
- new_hdr = kmalloc(SZ_SG_IO_HDR, GFP_KERNEL);
- if (!new_hdr) {
- retval = -ENOMEM;
- goto free_old_hdr;
- }
- retval =__copy_from_user
- (new_hdr, buf, SZ_SG_IO_HDR);
- req_pack_id = new_hdr->pack_id;
- kfree(new_hdr);
- if (retval) {
+ sg_io_hdr_t __user *p = (void __user *)buf;
+ if (get_user(req_pack_id, &p->pack_id)) {
retval = -EFAULT;
goto free_old_hdr;
}
--
2.11.0
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