RDMA/cxgb4: Fix potential null-ptr-deref in pass_establish()

If get_ep_from_tid() fails to lookup non-NULL value for ep, ep is
dereferenced later regardless of whether it is empty.
This patch adds a simple sanity check to fix the issue.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 944661dd97f4 ("RDMA/iw_cxgb4: atomically lookup ep and get a reference")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Link: https://lore.kernel.org/r/20230202184850.29882-1-n.zhandarovich@fintech.ru
Signed-off-by: Leon Romanovsky <leon@kernel.org>

diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index ea3ddf0d2411427d8621a47fefbe6643e0a63de9..ced615b5ea096ed58d4198ceaf8b960428d98ecd 100644 (file)
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -2676,6 +2676,9 @@ static int pass_establish(struct c4iw_dev *dev, struct sk_buff *skb)
        u16 tcp_opt = ntohs(req->tcp_opt);
 
        ep = get_ep_from_tid(dev, tid);
+       if (!ep)
+               return 0;
+
        pr_debug("ep %p tid %u\n", ep, ep->hwtid);
        ep->snd_seq = be32_to_cpu(req->snd_isn);
        ep->rcv_seq = be32_to_cpu(req->rcv_isn);