[PATCH V2 1/3] nvmet-tcp: Fix a kernel panic when host sends an invalid H2C PDU length

Maurizio Lombardi
2023-12-22T15:18:08Z

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@redhat.com>
---
drivers/nvme/target/tcp.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index 4cc27856aa8f..ad16795934b8 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -24,6 +24,7 @@
#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)
{
@@ -923,7 +924,7 @@ 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;
@@ -978,6 +979,7 @@ 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)) {
@@ -1001,7 +1003,16 @@ 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;
--
2.39.3