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firewire: cdev: fix 32 bit userland on 64 bit kernel compat corner cases

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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>
This commit is contained in:
Stefan Richter 2011-08-11 00:06:04 +02:00
parent 9a00c24ae7
commit 9c1176b6a2
1 changed files with 21 additions and 3 deletions
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24
drivers/firewire/core-cdev.c
View file

@ -216,15 +216,33 @@ struct inbound_phy_packet_event {
struct fw_cdev_event_phy_packet phy_packet; 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; 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) static int fw_device_op_open(struct inode *inode, struct file *file)
{ {