This is a note to let you know that I've just added the patch titled
USB: misc: yurex: fix race between read and write
to the 5.4-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:
usb-misc-yurex-fix-race-between-read-and-write.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit eca18fcac1723b0c8c9c52e1985ab22e3e117994
Author: Oliver Neukum <oneukum@xxxxxxxx>
Date: Thu Sep 12 15:21:22 2024 +0200
USB: misc: yurex: fix race between read and write
[ Upstream commit 93907620b308609c72ba4b95b09a6aa2658bb553 ]
The write code path touches the bbu member in a non atomic manner
without taking the spinlock. Fix it.
The bug is as old as the driver.
Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20240912132126.1034743-1-oneukum@xxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c
index a85cc0f3e15c4..5f271d25b633d 100644
--- a/drivers/usb/misc/yurex.c
+++ b/drivers/usb/misc/yurex.c
@@ -405,7 +405,6 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count,
struct usb_yurex *dev;
int len = 0;
char in_buffer[MAX_S64_STRLEN];
- unsigned long flags;
dev = file->private_data;
@@ -418,9 +417,9 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count,
if (WARN_ON_ONCE(dev->bbu > S64_MAX || dev->bbu < S64_MIN))
return -EIO;
- spin_lock_irqsave(&dev->lock, flags);
+ spin_lock_irq(&dev->lock);
scnprintf(in_buffer, MAX_S64_STRLEN, "%lld\n", dev->bbu);
- spin_unlock_irqrestore(&dev->lock, flags);
+ spin_unlock_irq(&dev->lock);
mutex_unlock(&dev->io_mutex);
return simple_read_from_buffer(buffer, count, ppos, in_buffer, len);
@@ -510,8 +509,11 @@ static ssize_t yurex_write(struct file *file, const char __user *user_buffer,
__func__, retval);
goto error;
}
- if (set && timeout)
+ if (set && timeout) {
+ spin_lock_irq(&dev->lock);
dev->bbu = c2;
+ spin_unlock_irq(&dev->lock);
+ }
return timeout ? count : -EIO;
error:
