From: Oliver Neukum Date: Thu, 12 Sep 2024 13:21:22 +0000 (+0200) Subject: USB: misc: yurex: fix race between read and write X-Git-Tag: v6.10.13~115 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9479f64b99927c04415f25ecd20f50ee740ec50b;p=thirdparty%2Fkernel%2Fstable.git USB: misc: yurex: fix race between read and write commit 93907620b308609c72ba4b95b09a6aa2658bb553 upstream. 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 CC: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240912132126.1034743-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c index 9a0649d236935..6adaaf66c14d7 100644 --- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -404,7 +404,6 @@ 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; @@ -419,9 +418,9 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, 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); @@ -511,8 +510,11 @@ 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: