[PATCH v2 4.19/5.4/5.10 1/1] RDMA/cxgb4: Fix potential null-ptr-deref in pass_establish()

[Nikita Zhandarovich]

From: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>

commit 283861a4c52c1ea4df3dd1b6fc75a50796ce3524 upstream.

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@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230202184850.29882-1-n.zhandarovich@xxxxxxxxxx
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
---
v2: Add stable maintainers as patch recepients.

 drivers/infiniband/hw/cxgb4/cm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index ea3ddf0d241142..ced615b5ea096e 100644
--- 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);
-- 
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