From: Al Viro <viro@zeniv.linux.org.uk>
Date: Thu, 23 Apr 2020 02:56:59 +0000 (-0400)
Subject: drivers/crypto/ccp/sev-dev.c: get rid of pointless access_ok()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=835ae3bb530a2e40dd5615c3728d4a78320f6fb8;p=linux.git

drivers/crypto/ccp/sev-dev.c: get rid of pointless access_ok()

Contrary to the comments, those do *NOT* verify anything about
writability of memory, etc.

In all cases addresses are passed only to copy_to_user().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 896f190b9a502..7f97164cbafbd 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -371,8 +371,7 @@ static int sev_ioctl_do_pek_csr(struct sev_issue_cmd *argp, bool writable)
 		goto cmd;
 
 	/* allocate a physically contiguous buffer to store the CSR blob */
-	if (!access_ok(input.address, input.length) ||
-	    input.length > SEV_FW_BLOB_MAX_SIZE) {
+	if (input.length > SEV_FW_BLOB_MAX_SIZE) {
 		ret = -EFAULT;
 		goto e_free;
 	}
@@ -609,12 +608,6 @@ static int sev_ioctl_do_get_id2(struct sev_issue_cmd *argp)
 	if (copy_from_user(&input, (void __user *)argp->data, sizeof(input)))
 		return -EFAULT;
 
-	/* Check if we have write access to the userspace buffer */
-	if (input.address &&
-	    input.length &&
-	    !access_ok(input.address, input.length))
-		return -EFAULT;
-
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
@@ -730,15 +723,13 @@ static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp, bool writable)
 		goto cmd;
 
 	/* Allocate a physically contiguous buffer to store the PDH blob. */
-	if ((input.pdh_cert_len > SEV_FW_BLOB_MAX_SIZE) ||
-	    !access_ok(input.pdh_cert_address, input.pdh_cert_len)) {
+	if (input.pdh_cert_len > SEV_FW_BLOB_MAX_SIZE) {
 		ret = -EFAULT;
 		goto e_free;
 	}
 
 	/* Allocate a physically contiguous buffer to store the cert chain blob. */
-	if ((input.cert_chain_len > SEV_FW_BLOB_MAX_SIZE) ||
-	    !access_ok(input.cert_chain_address, input.cert_chain_len)) {
+	if (input.cert_chain_len > SEV_FW_BLOB_MAX_SIZE) {
 		ret = -EFAULT;
 		goto e_free;
 	}