[PATCH] nvmet: fix heap out-of-bounds read in nvmet_auth_negotiate()

nvmet_execute_auth_send() allocates the DH-HMAC-CHAP message buffer with
the host-supplied transfer length (tl) and hands it to
nvmet_auth_negotiate() without passing tl along. nvmet_auth_negotiate()
then reads the negotiate header and, for each of the halen hash
identifiers and dhlen DH group identifiers, indexes into the fixed
idlist[60] array (hashes at idlist[0..halen), groups at idlist[30..]).

Neither the transfer length nor halen/dhlen is validated. A malicious or
non-conformant host can report a tl smaller than the negotiate structure,
or a halen/dhlen larger than the array (both are u8, up to 255), making
the loops read past the end of the allocated buffer (heap out-of-bounds
read). The sibling nvmet_auth_reply() already validates tl against the
structure size; the negotiate path did not.

Pass tl into nvmet_auth_negotiate(), reject a tl that does not cover the
negotiate data plus one full protocol descriptor, and reject halen/dhlen
larger than NVME_AUTH_DHCHAP_MAX_DH_IDS.

Fixes: db1312dd9548 ("nvmet: implement basic In-Band Authentication")
Signed-off-by: Guixin Liu <[email protected]>
---
 drivers/nvme/target/fabrics-cmd-auth.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/fabrics-cmd-auth.c b/drivers/nvme/target/fabrics-cmd-auth.c
index d1b39e64d877..d015968bae2d 100644
--- a/drivers/nvme/target/fabrics-cmd-auth.c
+++ b/drivers/nvme/target/fabrics-cmd-auth.c
@@ -31,12 +31,16 @@ void nvmet_auth_sq_init(struct nvmet_sq *sq)
 	sq->dhchap_step = NVME_AUTH_DHCHAP_MESSAGE_NEGOTIATE;
 }
 
-static u8 nvmet_auth_negotiate(struct nvmet_req *req, void *d)
+static u8 nvmet_auth_negotiate(struct nvmet_req *req, void *d, u32 tl)
 {
 	struct nvmet_ctrl *ctrl = req->sq->ctrl;
 	struct nvmf_auth_dhchap_negotiate_data *data = d;
 	int i, hash_id = 0, fallback_hash_id = 0, dhgid, fallback_dhgid;
 
+	if (tl < sizeof(*data) +
+		 sizeof(struct nvmf_auth_dhchap_protocol_descriptor))
+		return NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
+
 	pr_debug("%s: ctrl %d qid %d: data sc_d %d napd %d authid %d halen %d dhlen %d\n",
 		 __func__, ctrl->cntlid, req->sq->qid,
 		 data->sc_c, data->napd, data->auth_protocol[0].dhchap.authid,
@@ -72,6 +76,10 @@ static u8 nvmet_auth_negotiate(struct nvmet_req *req, void *d)
 	    NVME_AUTH_DHCHAP_AUTH_ID)
 		return NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
 
+	if (data->auth_protocol[0].dhchap.halen > NVME_AUTH_DHCHAP_MAX_DH_IDS ||
+	    data->auth_protocol[0].dhchap.dhlen > NVME_AUTH_DHCHAP_MAX_DH_IDS)
+		return NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
+
 	for (i = 0; i < data->auth_protocol[0].dhchap.halen; i++) {
 		u8 host_hmac_id = data->auth_protocol[0].dhchap.idlist[i];
 
@@ -317,7 +325,7 @@ void nvmet_execute_auth_send(struct nvmet_req *req)
 		} else if (data->auth_id != req->sq->dhchap_step)
 			goto done_failure1;
 		/* Validate negotiation parameters */
-		dhchap_status = nvmet_auth_negotiate(req, d);
+		dhchap_status = nvmet_auth_negotiate(req, d, tl);
 		if (dhchap_status == 0)
 			req->sq->dhchap_step =
 				NVME_AUTH_DHCHAP_MESSAGE_CHALLENGE;
-- 
2.43.7