Patch "nvmet-tcp: Fix a kernel panic when host sends an invalid H2C PDU length" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    nvmet-tcp: Fix a kernel panic when host sends an invalid H2C PDU length

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nvmet-tcp-fix-a-kernel-panic-when-host-sends-an-inva.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 29a3129183ea44e8b30fe351e8a14eb2ff99a348
Author: Maurizio Lombardi <mlombard@xxxxxxxxxx>
Date:   Fri Dec 22 16:17:48 2023 +0100

    nvmet-tcp: Fix a kernel panic when host sends an invalid H2C PDU length
    
    [ Upstream commit efa56305908ba20de2104f1b8508c6a7401833be ]
    
    If the host sends an H2CData command with an invalid DATAL,
    the kernel may crash in nvmet_tcp_build_pdu_iovec().
    
    Unable to handle kernel NULL pointer dereference at
    virtual address 0000000000000000
    lr : nvmet_tcp_io_work+0x6ac/0x718 [nvmet_tcp]
    Call trace:
      process_one_work+0x174/0x3c8
      worker_thread+0x2d0/0x3e8
      kthread+0x104/0x110
    
    Fix the bug by raising a fatal error if DATAL isn't coherent
    with the packet size.
    Also, the PDU length should never exceed the MAXH2CDATA parameter which
    has been communicated to the host in nvmet_tcp_handle_icreq().
    
    Fixes: 872d26a391da ("nvmet-tcp: add NVMe over TCP target driver")
    Signed-off-by: Maurizio Lombardi <mlombard@xxxxxxxxxx>
    Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
    Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index 197fc2ecb164..3d171061cc0f 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -19,6 +19,7 @@
 #include "nvmet.h"
 
 #define NVMET_TCP_DEF_INLINE_DATA_SIZE	(4 * PAGE_SIZE)
+#define NVMET_TCP_MAXH2CDATA		0x400000 /* 16M arbitrary limit */
 
 static int param_store_val(const char *str, int *val, int min, int max)
 {
@@ -900,7 +901,7 @@ static int nvmet_tcp_handle_icreq(struct nvmet_tcp_queue *queue)
 	icresp->hdr.pdo = 0;
 	icresp->hdr.plen = cpu_to_le32(icresp->hdr.hlen);
 	icresp->pfv = cpu_to_le16(NVME_TCP_PFV_1_0);
-	icresp->maxdata = cpu_to_le32(0x400000); /* 16M arbitrary limit */
+	icresp->maxdata = cpu_to_le32(NVMET_TCP_MAXH2CDATA);
 	icresp->cpda = 0;
 	if (queue->hdr_digest)
 		icresp->digest |= NVME_TCP_HDR_DIGEST_ENABLE;
@@ -953,6 +954,7 @@ static int nvmet_tcp_handle_h2c_data_pdu(struct nvmet_tcp_queue *queue)
 {
 	struct nvme_tcp_data_pdu *data = &queue->pdu.data;
 	struct nvmet_tcp_cmd *cmd;
+	unsigned int plen;
 
 	if (likely(queue->nr_cmds)) {
 		if (unlikely(data->ttag >= queue->nr_cmds)) {
@@ -976,7 +978,16 @@ static int nvmet_tcp_handle_h2c_data_pdu(struct nvmet_tcp_queue *queue)
 		return -EPROTO;
 	}
 
+	plen = le32_to_cpu(data->hdr.plen);
 	cmd->pdu_len = le32_to_cpu(data->data_length);
+	if (unlikely(cmd->pdu_len != (plen - sizeof(*data)) ||
+		     cmd->pdu_len == 0 ||
+		     cmd->pdu_len > NVMET_TCP_MAXH2CDATA)) {
+		pr_err("H2CData PDU len %u is invalid\n", cmd->pdu_len);
+		/* FIXME: use proper transport errors */
+		nvmet_tcp_fatal_error(queue);
+		return -EPROTO;
+	}
 	cmd->pdu_recv = 0;
 	nvmet_tcp_build_pdu_iovec(cmd);
 	queue->cmd = cmd;