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[020/178] kfifo: fix ternary sign extension bugs

Message ID 20210430055415.MjLQ2XY4b%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [001/178] arch/ia64/kernel/head.S: remove duplicate include | expand

Commit Message

Andrew Morton April 30, 2021, 5:54 a.m. UTC 
From: Dan Carpenter <dan.carpenter@oracle.com>
Subject: kfifo: fix ternary sign extension bugs

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>
---

 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(-)
diff mbox series

Patch

--- a/samples/kfifo/bytestream-example.c~kfifo-fix-ternary-sign-extension-bugs
+++ a/samples/kfifo/bytestream-example.c
@@ -122,8 +122,10 @@  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,
@@ -138,8 +140,10 @@  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 proc_ops fifo_proc_ops = {
--- a/samples/kfifo/inttype-example.c~kfifo-fix-ternary-sign-extension-bugs
+++ a/samples/kfifo/inttype-example.c
@@ -115,8 +115,10 @@  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,
@@ -131,8 +133,10 @@  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 proc_ops fifo_proc_ops = {
--- a/samples/kfifo/record-example.c~kfifo-fix-ternary-sign-extension-bugs
+++ a/samples/kfifo/record-example.c
@@ -129,8 +129,10 @@  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,
@@ -145,8 +147,10 @@  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 proc_ops fifo_proc_ops = {