From 926ee00ea24320052b46745ef4b00d91c05bd03d Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Thu, 29 Apr 2021 22:54:15 -0700 Subject: [PATCH] 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 Cc: Stefani Seibold Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c index c406f03..5a90aa5 100644 --- a/samples/kfifo/bytestream-example.c +++ b/samples/kfifo/bytestream-example.c @@ -122,8 +122,10 @@ static ssize_t fifo_write(struct file *file, const char __user *buf, 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 *file, char __user *buf, 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 = { diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c index 78977fc..e5403d8 100644 --- a/samples/kfifo/inttype-example.c +++ b/samples/kfifo/inttype-example.c @@ -115,8 +115,10 @@ static ssize_t fifo_write(struct file *file, const char __user *buf, 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 *file, char __user *buf, 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 = { diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c index c507998..f64f3d6 100644 --- a/samples/kfifo/record-example.c +++ b/samples/kfifo/record-example.c @@ -129,8 +129,10 @@ static ssize_t fifo_write(struct file *file, const char __user *buf, 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 *file, char __user *buf, 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 = { -- 2.7.4