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Thu, 21 May 2026 06:20:49 -0700 (PDT) Received: from csl-conti-dell7858.ntu.edu.sg ([155.69.195.57]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-36a45757364sm843594a91.5.2026.05.21.06.20.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 May 2026 06:20:49 -0700 (PDT) From: Maoyi Xie To: Chengchang Tang , Junxian Huang Cc: Jason Gunthorpe , Leon Romanovsky , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] RDMA/hns: fix dead empty check on head->root in setup_root_hem() Date: Thu, 21 May 2026 21:20:45 +0800 Message-Id: <20260521132045.3430906-1-maoyixie.tju@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" setup_root_hem() reads head->root with list_first_entry() and then tests the returned pointer against NULL. list_first_entry() never returns NULL. On an empty list it returns container_of(&head->root, struct hns_roce_hem_item, list), which equals &head->root because list is the first member. The -ENOMEM early return is dead code. If head->root is ever empty here, the aliased root_hem points at &head->root. root_hem->addr and root_hem->dma_addr then read past the end of struct hns_roce_hem_head into adjacent memory. The garbage value is handed to the hardware as a DMA base address. Use list_first_entry_or_null() so the empty case returns NULL and the -ENOMEM early return runs. The same shape has been cleaned up elsewhere, for example in commit fbb8bc408027 ("net: qed: Remove redundant NULL checks after list_fir= st_entry()"), commit c708d3fad421 ("crypto: atmel - use list_first_entry_or_null to simpl= ify find_dev"), and commit 10379171f346 ("ksmbd: use list_first_entry_or_null for opinfo_ge= t_list()"). This hns site was missed by those cleanups. Signed-off-by: Maoyi Xie --- drivers/infiniband/hw/hns/hns_roce_hem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/hw/hns/hns_roce_hem.c b/drivers/infiniband/= hw/hns/hns_roce_hem.c index e7c9e30ad2d8..12ac9ba6b312 100644 --- a/drivers/infiniband/hw/hns/hns_roce_hem.c +++ b/drivers/infiniband/hw/hns/hns_roce_hem.c @@ -1267,8 +1267,8 @@ setup_root_hem(struct hns_roce_dev *hr_dev, struct hn= s_roce_hem_list *hem_list, int i, total; int ret; =20 - root_hem =3D list_first_entry(&head->root, - struct hns_roce_hem_item, list); + root_hem =3D list_first_entry_or_null(&head->root, + struct hns_roce_hem_item, list); if (!root_hem) return -ENOMEM; =20 --=20 2.34.1