4.19-stable review patch. If anyone has any objections, please let me know.
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From: Oliver Neukum oneukum@suse.com
[ 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@suse.com CC: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240912132126.1034743-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/usb/misc/yurex.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
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: