From 926ee00ea24320052b46745ef4b00d91c05bd03d Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Thu, 29 Apr 2021 22:54:15 -0700
Subject: [PATCH] kfifo: fix ternary sign extension bugs
Git-commit: 926ee00ea24320052b46745ef4b00d91c05bd03d
References: git-fixes
Patch-mainline: v5.13-rc1

The intent with this code was to return negative error codes but instead
it returns positives.

The problem is how type promotion works with ternary operations.  These
functions return long, "ret" is an int and "copied" is a u32.  The
negative error code is first cast to u32 so it becomes a high positive and
then cast to long where it's still a positive.

We could fix this by declaring "ret" as a ssize_t but let's just get rid
of the ternaries instead.

Link: https://lkml.kernel.org/r/YIE+/cK1tBzSuQPU@mwanda
Fixes: 5bf2b19320ec ("kfifo: add example files to the kernel sample directory")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Stefani Seibold <stefani@seibold.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 samples/kfifo/bytestream-example.c |    8 ++++++--
 samples/kfifo/inttype-example.c    |    8 ++++++--
 samples/kfifo/record-example.c     |    8 ++++++--
 3 files changed, 18 insertions(+), 6 deletions(-)

--- a/samples/kfifo/bytestream-example.c
+++ b/samples/kfifo/bytestream-example.c
@@ -124,8 +124,10 @@ static ssize_t fifo_write(struct file *f
 	ret = kfifo_from_user(&test, buf, count, &copied);
 
 	mutex_unlock(&write_lock);
+	if (ret)
+		return ret;
 
-	return ret ? ret : copied;
+	return copied;
 }
 
 static ssize_t fifo_read(struct file *file, char __user *buf,
@@ -140,8 +142,10 @@ static ssize_t fifo_read(struct file *fi
 	ret = kfifo_to_user(&test, buf, count, &copied);
 
 	mutex_unlock(&read_lock);
+	if (ret)
+		return ret;
 
-	return ret ? ret : copied;
+	return copied;
 }
 
 static const struct file_operations fifo_fops = {
--- a/samples/kfifo/inttype-example.c
+++ b/samples/kfifo/inttype-example.c
@@ -117,8 +117,10 @@ static ssize_t fifo_write(struct file *f
 	ret = kfifo_from_user(&test, buf, count, &copied);
 
 	mutex_unlock(&write_lock);
+	if (ret)
+		return ret;
 
-	return ret ? ret : copied;
+	return copied;
 }
 
 static ssize_t fifo_read(struct file *file, char __user *buf,
@@ -133,8 +135,10 @@ static ssize_t fifo_read(struct file *fi
 	ret = kfifo_to_user(&test, buf, count, &copied);
 
 	mutex_unlock(&read_lock);
+	if (ret)
+		return ret;
 
-	return ret ? ret : copied;
+	return copied;
 }
 
 static const struct file_operations fifo_fops = {
--- a/samples/kfifo/record-example.c
+++ b/samples/kfifo/record-example.c
@@ -131,8 +131,10 @@ static ssize_t fifo_write(struct file *f
 	ret = kfifo_from_user(&test, buf, count, &copied);
 
 	mutex_unlock(&write_lock);
+	if (ret)
+		return ret;
 
-	return ret ? ret : copied;
+	return copied;
 }
 
 static ssize_t fifo_read(struct file *file, char __user *buf,
@@ -147,8 +149,10 @@ static ssize_t fifo_read(struct file *fi
 	ret = kfifo_to_user(&test, buf, count, &copied);
 
 	mutex_unlock(&read_lock);
+	if (ret)
+		return ret;
 
-	return ret ? ret : copied;
+	return copied;
 }
 
 static const struct file_operations fifo_fops = {