firewire: cdev: fix 32 bit userland on 64 bit kernel compat corner cases
Clemens points out that we need to use compat_ptr() in order to safely
cast from u64 to addresses of a 32-bit usermode client.
Before, our conversion went wrong
- in practice if the client cast from pointer to integer such that
sign-extension happened, (libraw1394 and libdc1394 at least were not
doing that, IOW were not affected)
or
- in theory on s390 (which doesn't have FireWire though) and on the
tile architecture, regardless of what the client does.
The bug would usually be observed as the initial get_info ioctl failing
with "Bad address" (EFAULT).
Reported-by: Carl Karsten <carl@personnelware.com>
Reported-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index e6ad3bb..4799393 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -216,15 +216,33 @@
struct fw_cdev_event_phy_packet phy_packet;
};
-static inline void __user *u64_to_uptr(__u64 value)
+#ifdef CONFIG_COMPAT
+static void __user *u64_to_uptr(u64 value)
+{
+ if (is_compat_task())
+ return compat_ptr(value);
+ else
+ return (void __user *)(unsigned long)value;
+}
+
+static u64 uptr_to_u64(void __user *ptr)
+{
+ if (is_compat_task())
+ return ptr_to_compat(ptr);
+ else
+ return (u64)(unsigned long)ptr;
+}
+#else
+static inline void __user *u64_to_uptr(u64 value)
{
return (void __user *)(unsigned long)value;
}
-static inline __u64 uptr_to_u64(void __user *ptr)
+static inline u64 uptr_to_u64(void __user *ptr)
{
- return (__u64)(unsigned long)ptr;
+ return (u64)(unsigned long)ptr;
}
+#endif /* CONFIG_COMPAT */
static int fw_device_op_open(struct inode *inode, struct file *file)
{
