Commit c35a5cfb authored Oct 17, 2019 by Al Viro Committed by Martin K. Petersen Nov 06, 2019

scsi: sg: sg_read(): simplify reading ->pack_id of userland sg_io_hdr_t

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...

Link: https://lore.kernel.org/r/20191017193925.25539-4-viro@ZenIV.linux.org.uk


Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

parent 062c9d45

drivers/scsi/sg.c

+2 −11

Original line number	Diff line number	Diff line
		@@ -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;
		}

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