This is a note to let you know that I've just added the patch titled
kfifo: fix ternary sign extension bugs
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kfifo-fix-ternary-sign-extension-bugs.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 09195167b9300ae3ba9ebdf0e18701fbe4ecf6e7
Author: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Date: Thu Apr 29 22:54:15 2021 -0700
kfifo: fix ternary sign extension bugs
[ Upstream commit 926ee00ea24320052b46745ef4b00d91c05bd03d ]
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@xxxxxxxxxx>
Cc: Stefani Seibold <stefani@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c
index 2fca916d9edf..a7f5ee8b6edc 100644
--- a/samples/kfifo/bytestream-example.c
+++ b/samples/kfifo/bytestream-example.c
@@ -124,8 +124,10 @@ 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,
@@ -140,8 +142,10 @@ 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 file_operations fifo_fops = {
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
index 8dc3c2e7105a..a326a37e9163 100644
--- a/samples/kfifo/inttype-example.c
+++ b/samples/kfifo/inttype-example.c
@@ -117,8 +117,10 @@ 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,
@@ -133,8 +135,10 @@ 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 file_operations fifo_fops = {
diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c
index 2d7529eeb294..deb87a2e4e6b 100644
--- a/samples/kfifo/record-example.c
+++ b/samples/kfifo/record-example.c
@@ -131,8 +131,10 @@ 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,
@@ -147,8 +149,10 @@ 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 file_operations fifo_fops = {
