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-rw-r--r--fs/file.c17
-rw-r--r--include/linux/file.h7
-rw-r--r--net/compat.c2
-rw-r--r--net/core/scm.c2
4 files changed, 19 insertions, 9 deletions
diff --git a/fs/file.c b/fs/file.c
index 0cd598cab476..56d96d5c0c9f 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -944,12 +944,13 @@ out_unlock:
  * @o_flags: the O_* flags to apply to the new fd entry
  *
  * Installs a received file into the file descriptor table, with appropriate
- * checks and count updates. Writes the fd number to userspace.
+ * checks and count updates. Optionally writes the fd number to userspace, if
+ * @ufd is non-NULL.
  *
  * This helper handles its own reference counting of the incoming
  * struct file.
  *
- * Returns -ve on error.
+ * Returns newly install fd or -ve on error.
  */
 int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)
 {
@@ -964,16 +965,18 @@ int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)
 	if (new_fd < 0)
 		return new_fd;
 
-	error = put_user(new_fd, ufd);
-	if (error) {
-		put_unused_fd(new_fd);
-		return error;
+	if (ufd) {
+		error = put_user(new_fd, ufd);
+		if (error) {
+			put_unused_fd(new_fd);
+			return error;
+		}
 	}
 
 	/* Bump the sock usage counts, if any. */
 	__receive_sock(file);
 	fd_install(new_fd, get_file(file));
-	return 0;
+	return new_fd;
 }
 
 static int ksys_dup3(unsigned int oldfd, unsigned int newfd, int flags)
diff --git a/include/linux/file.h b/include/linux/file.h
index b14ff2ffd0bd..d9fee9f5c8da 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -9,6 +9,7 @@
 #include <linux/compiler.h>
 #include <linux/types.h>
 #include <linux/posix_types.h>
+#include <linux/errno.h>
 
 struct file;
 
@@ -96,8 +97,14 @@ extern int __receive_fd(struct file *file, int __user *ufd,
 static inline int receive_fd_user(struct file *file, int __user *ufd,
 				  unsigned int o_flags)
 {
+	if (ufd == NULL)
+		return -EFAULT;
 	return __receive_fd(file, ufd, o_flags);
 }
+static inline int receive_fd(struct file *file, unsigned int o_flags)
+{
+	return __receive_fd(file, NULL, o_flags);
+}
 
 extern void flush_delayed_fput(void);
 extern void __fput_sync(struct file *);
diff --git a/net/compat.c b/net/compat.c
index e74cd3dae8b0..dc7ddbc2b15e 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -299,7 +299,7 @@ void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm)
 
 	for (i = 0; i < fdmax; i++) {
 		err = receive_fd_user(scm->fp->fp[i], cmsg_data + i, o_flags);
-		if (err)
+		if (err < 0)
 			break;
 	}
 
diff --git a/net/core/scm.c b/net/core/scm.c
index 67c166a7820d..8156d4fb8a39 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -307,7 +307,7 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
 
 	for (i = 0; i < fdmax; i++) {
 		err = receive_fd_user(scm->fp->fp[i], cmsg_data + i, o_flags);
-		if (err)
+		if (err < 0)
 			break;
 	}