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[99.235.148.253]) by smtp.gmail.com with UTF8SMTPSA id u10-20020a05620a430a00b006ce7cd81359sm14275704qko.110.2022.10.11.18.40.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 11 Oct 2022 18:40:09 -0700 (PDT) From: Cezar Bulinaru To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org Cc: cbulinaru@gmail.com Subject: [PATCH v2] hv_netvsc: Fix a warning triggered by memcpy in rndis_filter Date: Tue, 11 Oct 2022 21:39:22 -0400 Message-Id: <20221012013922.32374-1-cbulinaru@gmail.com> X-Mailer: git-send-email 2.37.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org A warning is triggered when the response message len exceeds the size of rndis_message. Inside the rndis_request structure these fields are however followed by a RNDIS_EXT_LEN padding so it is safe to use unsafe_memcpy. memcpy: detected field-spanning write (size 168) of single field "(void *)&request->response_msg + (sizeof(struct rndis_message) - sizeof(union rndis_message_container)) + sizeof(*req_id)" at drivers/net/hyperv/rndis_filter.c:338 (size 40) RSP: 0018:ffffc90000144de0 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff8881766b4000 RCX: 0000000000000000 RDX: 0000000000000102 RSI: 0000000000009ffb RDI: 00000000ffffffff RBP: ffffc90000144e38 R08: 0000000000000000 R09: 00000000ffffdfff R10: ffffc90000144c48 R11: ffffffff82f56ac8 R12: ffff8881766b403c R13: 00000000000000a8 R14: ffff888100b75000 R15: ffff888179301d00 FS: 0000000000000000(0000) GS:ffff8884d6280000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055f8b024c418 CR3: 0000000176548001 CR4: 00000000003706e0 Call Trace: ? _raw_spin_unlock_irqrestore+0x27/0x50 netvsc_poll+0x556/0x940 [hv_netvsc] __napi_poll+0x2e/0x170 net_rx_action+0x299/0x2f0 __do_softirq+0xed/0x2ef __irq_exit_rcu+0x9f/0x110 irq_exit_rcu+0xe/0x20 sysvec_hyperv_callback+0xb0/0xd0 asm_sysvec_hyperv_callback+0x1b/0x20 RIP: 0010:native_safe_halt+0xb/0x10 Signed-off-by: Cezar Bulinaru Reviewed-by: Michael Kelley --- drivers/net/hyperv/rndis_filter.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c index 11f767a20444..eea777ec2541 100644 --- a/drivers/net/hyperv/rndis_filter.c +++ b/drivers/net/hyperv/rndis_filter.c @@ -20,6 +20,7 @@ #include #include #include +#include #include "hyperv_net.h" #include "netvsc_trace.h" @@ -335,9 +336,10 @@ static void rndis_filter_receive_response(struct net_device *ndev, if (resp->msg_len <= sizeof(struct rndis_message) + RNDIS_EXT_LEN) { memcpy(&request->response_msg, resp, RNDIS_HEADER_SIZE + sizeof(*req_id)); - memcpy((void *)&request->response_msg + RNDIS_HEADER_SIZE + sizeof(*req_id), + unsafe_memcpy((void *)&request->response_msg + RNDIS_HEADER_SIZE + sizeof(*req_id), data + RNDIS_HEADER_SIZE + sizeof(*req_id), - resp->msg_len - RNDIS_HEADER_SIZE - sizeof(*req_id)); + resp->msg_len - RNDIS_HEADER_SIZE - sizeof(*req_id), + "request->response_msg is followed by a padding of RNDIS_EXT_LEN inside rndis_request"); if (request->request_msg.ndis_msg_type == RNDIS_MSG_QUERY && request->request_msg.msg. query_req.oid == RNDIS_OID_GEN_MEDIA_CONNECT_STATUS)