1 files changed, 26 insertions, 30 deletions

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index eff88a5f5d40..4743d71e4aa6 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -26,6 +26,8 @@
 #include <asm/uaccess.h>
 #include "internal.h"
 
+#define KEY_MAX_DESC_SIZE 4096
+
 static int key_get_type_from_user(char *type,
 				  const char __user *_type,
 				  unsigned len)
@@ -78,7 +80,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type,
 
 	description = NULL;
 	if (_description) {
-		description = strndup_user(_description, PAGE_SIZE);
+		description = strndup_user(_description, KEY_MAX_DESC_SIZE);
 		if (IS_ERR(description)) {
 			ret = PTR_ERR(description);
 			goto error;
@@ -177,7 +179,7 @@ SYSCALL_DEFINE4(request_key, const char __user *, _type,
 		goto error;
 
 	/* pull the description into kernel space */
-	description = strndup_user(_description, PAGE_SIZE);
+	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
 	if (IS_ERR(description)) {
 		ret = PTR_ERR(description);
 		goto error;
@@ -287,7 +289,7 @@ long keyctl_join_session_keyring(const char __user *_name)
 	/* fetch the name from userspace */
 	name = NULL;
 	if (_name) {
-		name = strndup_user(_name, PAGE_SIZE);
+		name = strndup_user(_name, KEY_MAX_DESC_SIZE);
 		if (IS_ERR(name)) {
 			ret = PTR_ERR(name);
 			goto error;
@@ -562,8 +564,9 @@ long keyctl_describe_key(key_serial_t keyid,
 {
 	struct key *key, *instkey;
 	key_ref_t key_ref;
-	char *tmpbuf;
+	char *infobuf;
 	long ret;
+	int desclen, infolen;
 
 	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
 	if (IS_ERR(key_ref)) {
@@ -586,38 +589,31 @@ long keyctl_describe_key(key_serial_t keyid,
 	}
 
 okay:
-	/* calculate how much description we're going to return */
-	ret = -ENOMEM;
-	tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!tmpbuf)
-		goto error2;
-
 	key = key_ref_to_ptr(key_ref);
+	desclen = strlen(key->description);
 
-	ret = snprintf(tmpbuf, PAGE_SIZE - 1,
-		       "%s;%d;%d;%08x;%s",
-		       key->type->name,
-		       from_kuid_munged(current_user_ns(), key->uid),
-		       from_kgid_munged(current_user_ns(), key->gid),
-		       key->perm,
-		       key->description ?: "");
-
-	/* include a NUL char at the end of the data */
-	if (ret > PAGE_SIZE - 1)
-		ret = PAGE_SIZE - 1;
-	tmpbuf[ret] = 0;
-	ret++;
+	/* calculate how much information we're going to return */
+	ret = -ENOMEM;
+	infobuf = kasprintf(GFP_KERNEL,
+			    "%s;%d;%d;%08x;",
+			    key->type->name,
+			    from_kuid_munged(current_user_ns(), key->uid),
+			    from_kgid_munged(current_user_ns(), key->gid),
+			    key->perm);
+	if (!infobuf)
+		goto error2;
+	infolen = strlen(infobuf);
+	ret = infolen + desclen + 1;
 
 	/* consider returning the data */
-	if (buffer && buflen > 0) {
-		if (buflen > ret)
-			buflen = ret;
-
-		if (copy_to_user(buffer, tmpbuf, buflen) != 0)
+	if (buffer && buflen >= ret) {
+		if (copy_to_user(buffer, infobuf, infolen) != 0 ||
+		    copy_to_user(buffer + infolen, key->description,
+				 desclen + 1) != 0)
 			ret = -EFAULT;
 	}
 
-	kfree(tmpbuf);
+	kfree(infobuf);
 error2:
 	key_ref_put(key_ref);
 error:
@@ -649,7 +645,7 @@ long keyctl_keyring_search(key_serial_t ringid,
 	if (ret < 0)
 		goto error;
 
-	description = strndup_user(_description, PAGE_SIZE);
+	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
 	if (IS_ERR(description)) {
 		ret = PTR_ERR(description);
 		goto error;