net/sched: taprio: always validate TCA_TAPRIO_ATTR_PRIOMAP

Origin: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit?id=3e102bb4e13ae49c014096f149ed0c8430e3c1f0
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2024-36974

[ Upstream commit f921a58ae20852d188f70842431ce6519c4fdc36 ]

If one TCA_TAPRIO_ATTR_PRIOMAP attribute has been provided,
taprio_parse_mqprio_opt() must validate it, or userspace
can inject arbitrary data to the kernel, the second time
taprio_change() is called.

First call (with valid attributes) sets dev->num_tc
to a non zero value.

Second call (with arbitrary mqprio attributes)
returns early from taprio_parse_mqprio_opt()
and bad things can happen.

Fixes: a3d43c0d56f1 ("taprio: Add support adding an admin schedule")
Reported-by: Noam Rathaus <noamr@ssd-disclosure.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20240604181511.769870-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name net-sched-taprio-always-validate-TCA_TAPRIO_ATTR_PRI.patch

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 1d4638aa4254fd00384f977f888a836f3154ef05..41187bbd25ee9a87b654aad83a19ca6d75d91375 100644 (file)
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -938,16 +938,13 @@ static int taprio_parse_mqprio_opt(struct net_device *dev,
 {
        int i, j;
 
-       if (!qopt && !dev->num_tc) {
-               NL_SET_ERR_MSG(extack, "'mqprio' configuration is necessary");
-               return -EINVAL;
-       }
-
-       /* If num_tc is already set, it means that the user already
-        * configured the mqprio part
-        */
-       if (dev->num_tc)
+       if (!qopt) {
+               if (!dev->num_tc) {
+                       NL_SET_ERR_MSG(extack, "'mqprio' configuration is necessary");
+                       return -EINVAL;
+               }
                return 0;
+       }
 
        /* Verify num_tc is not out of max range */
        if (qopt->num_tc > TC_MAX_QUEUE) {