From: Wenwen Wang <wang6...@umn.edu> Date: Mon, 30 Apr 2018 12:31:13 -0500
> In ethtool_get_rxnfc(), the object "info" is firstly copied from > user-space. If the FLOW_RSS flag is set in the member field flow_type of > "info" (and cmd is ETHTOOL_GRXFH), info needs to be copied again from > user-space because FLOW_RSS is newer and has new definition, as mentioned > in the comment. However, given that the user data resides in user-space, a > malicious user can race to change the data after the first copy. By doing > so, the user can inject inconsistent data. For example, in the second > copy, the FLOW_RSS flag could be cleared in the field flow_type of "info". > In the following execution, "info" will be used in the function > ops->get_rxnfc(). Such inconsistent data can potentially lead to unexpected > information leakage since ops->get_rxnfc() will prepare various types of > data according to flow_type, and the prepared data will be eventually > copied to user-space. This inconsistent data may also cause undefined > behaviors based on how ops->get_rxnfc() is implemented. > > This patch simply re-verifies the flow_type field of "info" after the > second copy. If the value is not as expected, an error code will be > returned. > > Signed-off-by: Wenwen Wang <wang6...@umn.edu> Applied, thanks.
