A denial of service flaw was discovered in the Linux kernel, where a race condition caused a NULL pointer dereference in the RDS socket-creation code. A local attacker could use this flaw to create a situation in which a NULL pointer crashed the kernel.
A NULL pointer dereference in the RDS connection code when sending a message to an apparently unbound socket in net/rds/connection.c was found. The problem is caused by the code checking if the socket is bound in rds_sendmsg(), which checks the rs_bound_addr field without taking a lock on the socket. This opens a race where rs_bound_addr is temporarily set but where the transport is not in rds_bind(), leading to a NULL pointer dereference when trying to dereference 'trans' in __rds_conn_create().
Note that this is a complete fix of CVE-2015-6937 issue.
Patch can be found here:
The Linux kernel will attempt to automatically load the RDS module when the RDS protocol is used from userspace. The module can be prevented being loaded with the commands:
echo "install rds /bin/true" > /etc/modprobe.d/disable-rds
echo "alias net-pf-28 off" >> /etc/modprobe.d/disable-rds
Earlier versions of Red Hat Enterprise Linux can be disabled with instructions from here: https://access.redhat.com/solutions/41278
If the module is already loaded prior to this, it must be removed or the system must be rebooted to preven it loading in the future.
Created kernel tracking bugs for this issue:
Affects: fedora-all [bug 1276438]
kernel-4.2.6-300.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.
kernel-4.2.6-200.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.
kernel-4.1.13-100.fc21 has been pushed to the Fedora 21 stable repository. If problems still persist, please make note of it in this bug report.
This issue affects Red Hat enterprise Linux 5 and 6. The affected code is not available in 7, MRG and realtime kernels.