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authorStefan Richter <stefanr@s5r6.in-berlin.de>2010-04-07 08:30:50 +0200
committerStefan Richter <stefanr@s5r6.in-berlin.de>2010-04-10 16:51:13 +0200
commit9cac00b8f0079d5d3d54ec4dae453d58dec30e7c (patch)
tree902b5f22c553395e5bab8c7561b996f19584e7f6 /drivers
parent385ab5bcd4be586dffdba550b310308d89eade71 (diff)
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firewire: cdev: fix information leak
A userspace client got to see uninitialized stack-allocated memory if it specified an _IOC_READ type of ioctl and an argument size larger than expected by firewire-core's ioctl handlers (but not larger than the core's union ioctl_arg). Fix this by clearing the requested buffer size to zero, but only at _IOR ioctls. This way, there is almost no runtime penalty to legitimate ioctls. The only legitimate _IOR is FW_CDEV_IOC_GET_CYCLE_TIMER with 12 or 16 bytes to memset. [Another way to fix this would be strict checking of argument size (and possibly direction) vs. command number. However, we then need a lookup table, and we need to allow for slight size deviations in case of 32bit userland on 64bit kernel.] Reported-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/firewire/core-cdev.c18
1 files changed, 9 insertions, 9 deletions
diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index 5eba9e0f876..0d3df0927ef 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -1356,24 +1356,24 @@ static int dispatch_ioctl(struct client *client,
return -ENODEV;
if (_IOC_TYPE(cmd) != '#' ||
- _IOC_NR(cmd) >= ARRAY_SIZE(ioctl_handlers))
+ _IOC_NR(cmd) >= ARRAY_SIZE(ioctl_handlers) ||
+ _IOC_SIZE(cmd) > sizeof(buffer))
return -EINVAL;
- if (_IOC_DIR(cmd) & _IOC_WRITE) {
- if (_IOC_SIZE(cmd) > sizeof(buffer) ||
- copy_from_user(&buffer, arg, _IOC_SIZE(cmd)))
+ if (_IOC_DIR(cmd) == _IOC_READ)
+ memset(&buffer, 0, _IOC_SIZE(cmd));
+
+ if (_IOC_DIR(cmd) & _IOC_WRITE)
+ if (copy_from_user(&buffer, arg, _IOC_SIZE(cmd)))
return -EFAULT;
- }
ret = ioctl_handlers[_IOC_NR(cmd)](client, &buffer);
if (ret < 0)
return ret;
- if (_IOC_DIR(cmd) & _IOC_READ) {
- if (_IOC_SIZE(cmd) > sizeof(buffer) ||
- copy_to_user(arg, &buffer, _IOC_SIZE(cmd)))
+ if (_IOC_DIR(cmd) & _IOC_READ)
+ if (copy_to_user(arg, &buffer, _IOC_SIZE(cmd)))
return -EFAULT;
- }
return ret;
}