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| author | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2010-04-07 06:30:50 (GMT) |
|---|---|---|
| committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2010-04-10 14:51:13 (GMT) |
| commit | 9cac00b8f0079d5d3d54ec4dae453d58dec30e7c (patch) | |
| tree | 902b5f22c553395e5bab8c7561b996f19584e7f6 /drivers | |
| parent | 385ab5bcd4be586dffdba550b310308d89eade71 (diff) | |
| download | linux-9cac00b8f0079d5d3d54ec4dae453d58dec30e7c.tar.xz | |
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.c | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c index 5eba9e0..0d3df09 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; } |