From e324461bd46aecb962c8bffc02283d0ebca3c5ab 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: 113399f9a59c ("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 c406f03ee5519..5a90aa5278775 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 78977fc4a23f7..e5403d8c971a5 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 c507998a2617c..f64f3d62d6c2a 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 = { -- 2.39.5