usb: mdc800: handle signal and read racing

oneukum · gregkh · commit 2d6d260e9a35 · 2026-02-25T10:26:46.000-08:00
If a signal arrives after a read has partially completed, we need to return the number of bytes read. -EINTR is correct only if that number is zero. Signed-off-by: Oliver Neukum <oneukum@suse.com> Cc: stable <stable@kernel.org> Link: https://patch.msgid.link/20260209142048.1503791-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/image/mdc800.c b/drivers/usb/image/mdc800.c
@@ -707,7 +707,7 @@ static ssize_t mdc800_device_read (struct file *file, char __user *buf, size_t l
 		if (signal_pending (current)) 
 		{
 			mutex_unlock(&mdc800->io_lock);
-			return -EINTR;
+			return len == left ? -EINTR : len-left;
 		}
 
 		sts=left > (mdc800->out_count-mdc800->out_ptr)?mdc800->out_count-mdc800->out_ptr:left;

Original file line number	Diff line number	Diff line change
`@@ -707,7 +707,7 @@ static ssize_t mdc800_device_read (struct file file, char __user buf, size_t l`
`707`	`707`	`if (signal_pending (current))`
`708`	`708`	`{`
`709`	`709`	`mutex_unlock(&mdc800->io_lock);`
`710`		`- return -EINTR;`
	`710`	`+ return len == left ? -EINTR : len-left;`
`711`	`711`	`}`
`712`	`712`
`713`	`713`	`sts=left > (mdc800->out_count-mdc800->out_ptr)?mdc800->out_count-mdc800->out_ptr:left;`