u32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode through the walker callback. u32_bind_class() unconditionally casts the passed fh to tc_u_knode and accesses &n->res, so when fh is actually a tc_u_hnode, which has no tcf_result member, this results in a slab-out-of-bounds read of res->classid in tc_cls_bind_class(). The issue can be reproduced with the following commands: tc qdisc add dev lo root handle 1: hfsc tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1 tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit Fix this by skipping hash tables via the TC_U32_KEY(handle) check. Fixes: 07d79fc7d94e ("net_sched: add reverse binding for tc class") Signed-off-by: Zhang Changzhong --- net/sched/cls_u32.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 34d25f7..90ad80b 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -1250,6 +1250,9 @@ static void u32_bind_class(void *fh, u32 classid, unsigned long cl, void *q, { struct tc_u_knode *n = fh; + if (TC_U32_KEY(n->handle) == 0) + return; + tc_cls_bind_class(classid, cl, q, &n->res, base); } -- 2.9.5