[PATCH v3] nfc: nci: ignore unexpected CORE_RESET_NTF and CORE_RESET_RSP

[Yuchao Zhang <ndaugoing@gmail.com>]

Commit bcd684aace34 ("net/nfc/nci: Support NCI 2.x initial sequence")
added handling of CORE_RESET_NTF in nci_core_reset_ntf_packet(). When
received, it updates ndev->nci_ver, ndev->manufact_id, and
ndev->manufact_specific_info, and calls nci_req_complete(ndev,
NCI_STATUS_OK) to finish the pending reset request.

However, unlike other notification handlers in ntf.c (which validate
ndev->state before completing requests), nci_core_reset_ntf_packet()
does not check whether a core reset request is actually pending.
If an unsolicited or delayed CORE_RESET_NTF arrives (e.g. after a reset
command times out or from a misbehaving NFCC), it unconditionally:
1. Completes whatever request is currently in-flight (such as CORE_INIT,
   RF_DISCOVER, or CONN_CREATE) with NCI_STATUS_OK, leading to kernel
   state desynchronization.
2. Overwrites ndev->nci_ver and manufacturer info. Because
   ndev->nci_ver is used as a selector for subsequent packet formats
   and parsers (e.g., in nci_open_device() and nci_core_init_rsp_packet()),
   unexpectedly modifying it can cause protocol format confusion.

A similar issue exists in nci_core_reset_rsp_packet(): an unexpected or
delayed response packet can prematurely complete an unrelated in-flight
request.

Fix this by ensuring CORE_RESET_NTF and CORE_RESET_RSP are only processed
by the core layer when a reset command is actively awaiting them:
- Set NCI_RESET_PENDING in nci_reset_req() when sending CORE_RESET_CMD.
- In nci_core_reset_rsp_packet(), ignore the response if NCI_RESET_PENDING
  is not set. If set, atomically clear the flag and complete the request
  on failure or for NCI 1.x (checking skb->len >= sizeof(*rsp)).
- In __nci_request(), ensure NCI_RESET_PENDING is cleared upon request
  completion, cancellation, or timeout.
- In nci_core_reset_ntf_packet(), fail any in-flight reset request if the
  controller reports an unrecoverable error (0x00), and only process
  command-triggered notifications (0x02). Non-command triggers (e.g.
  power-on 0x01 or proprietary triggers) and unexpected notifications
  return 0 without modifying core state, ensuring driver-specific
  notification handlers (such as fdp firmware patch handling) still
  receive them.
- In nci_core_reset_ntf_packet(), support notifications shorter than 9
  bytes (e.g. NCI 2.0 frames with manufacturer_specific_len == 0),
  validating the fixed header length and safely bounding
  manufact_specific_info reads.

Fixes: bcd684aace34 ("net/nfc/nci: Support NCI 2.x initial sequence")
Cc: stable@vger.kernel.org
Signed-off-by: Yuchao Zhang <ndaugoing@gmail.com>
---
v3:
 - In nci_core_reset_ntf_packet(), do not reject notifications shorter than
   9 bytes with -EINVAL; instead allow valid short frames (e.g. 2-byte NCI 1.x
   or 5-byte NCI 2.0 with manufacturer_specific_len == 0), safely cap field
   reads, and return 0 so driver-registered hooks (such as fdp firmware
   patching) are not skipped (per Sashiko AI).
 - Fix trigger semantics: in NCI, CORE_RESET_CMD trigger is 0x02
   (NCI_RESET_TRIGGER_RESET_CMD). If controller reports an unrecoverable error
   (0x00, NCI_RESET_TRIGGER_ERROR) while reset is pending, fail the request
   instead of completing with OK; ignore power-on (0x01) and proprietary
   triggers at core layer (per Sashiko AI).
 - In nci_core_reset_rsp_packet(), use test_and_clear_bit(NCI_RESET_PENDING)
   upon completing the request to consume the flag atomically (per Sashiko AI).
 - Link to v2: https://lore.kernel.org/netdev/20260922102144.39689-1-ndaugoing@gmail.com/

v2:
 - Do not abort the notification pipeline on unexpected CORE_RESET_NTF (return 0
   instead of -EINVAL), preserving driver-level hooks (e.g. fdp firmware
   patching) per Simon Horman.
 - Skip power-on notifications (trigger 0x01, identical in NCI 1.0 and 2.0)
   while gating both NCI 1.0 (0x00) and NCI 2.0 (0x02) command-triggered resets
   on NCI_RESET_PENDING alone.
 - Check NCI_RESET_PENDING in nci_core_reset_rsp_packet() to avoid completing
   unrelated requests on unexpected responses.
 - Explicitly check skb->len >= sizeof(*rsp) in nci_core_reset_rsp_packet()
   for NCI 1.x handling.
 - Link to v1: https://lore.kernel.org/netdev/20260918013337.82214-1-ndaugoing@gmail.com/

 include/net/nfc/nci.h      |  5 ++++
 include/net/nfc/nci_core.h |  1 +
 net/nfc/nci/core.c         |  3 +++
 net/nfc/nci/ntf.c          | 48 +++++++++++++++++++++++++++++++++-----
 net/nfc/nci/rsp.c          | 30 ++++++++++++++++++------
 5 files changed, 74 insertions(+), 13 deletions(-)

diff --git a/include/net/nfc/nci.h b/include/net/nfc/nci.h
index 09efcaed7c3f..2ac45adba088 100644
--- a/include/net/nfc/nci.h
+++ b/include/net/nfc/nci.h
@@ -140,6 +140,11 @@
 #define NCI_RESET_TYPE_KEEP_CONFIG				0x00
 #define NCI_RESET_TYPE_RESET_CONFIG				0x01
 
+/* NCI Reset Triggers */
+#define NCI_RESET_TRIGGER_ERROR					0x00
+#define NCI_RESET_TRIGGER_POWER_ON				0x01
+#define NCI_RESET_TRIGGER_RESET_CMD				0x02
+
 /* NCI Static RF connection ID */
 #define NCI_STATIC_RF_CONN_ID					0x00
 
diff --git a/include/net/nfc/nci_core.h b/include/net/nfc/nci_core.h
index 664d5058e66e..504ea91ddf27 100644
--- a/include/net/nfc/nci_core.h
+++ b/include/net/nfc/nci_core.h
@@ -31,6 +31,7 @@ enum nci_flag {
 	NCI_DATA_EXCHANGE,
 	NCI_DATA_EXCHANGE_TO,
 	NCI_UNREG,
+	NCI_RESET_PENDING,
 };
 
 /* NCI device states */
diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c
index 5f46c4b5720f..5a90591cd9af 100644
--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -134,6 +134,7 @@ static int __nci_request(struct nci_dev *ndev,
 	}
 
 	ndev->req_status = ndev->req_result = 0;
+	clear_bit(NCI_RESET_PENDING, &ndev->flags);
 
 	return rc;
 }
@@ -163,6 +164,8 @@ static void nci_reset_req(struct nci_dev *ndev, const void *opt)
 {
 	struct nci_core_reset_cmd cmd;
 
+	set_bit(NCI_RESET_PENDING, &ndev->flags);
+
 	cmd.reset_type = NCI_RESET_TYPE_RESET_CONFIG;
 	nci_send_cmd(ndev, NCI_OP_CORE_RESET_CMD, 1, &cmd);
 }
diff --git a/net/nfc/nci/ntf.c b/net/nfc/nci/ntf.c
index f5c9a8ab7ec1..81ba6011c027 100644
--- a/net/nfc/nci/ntf.c
+++ b/net/nfc/nci/ntf.c
@@ -30,21 +30,57 @@
 static int nci_core_reset_ntf_packet(struct nci_dev *ndev,
 				     const struct sk_buff *skb)
 {
-	/* Handle NCI 2.x core reset notification */
 	const struct nci_core_reset_ntf *ntf;
 
-	if (skb->len < sizeof(struct nci_core_reset_ntf))
-		return -EINVAL;
+	/*
+	 * Return 0 on short or unhandled packets so driver-specific
+	 * notification hooks (such as fdp firmware patching) can still run.
+	 */
+	if (skb->len < 2)
+		return 0;
 
-	ntf = (struct nci_core_reset_ntf *)skb->data;
+	ntf = (const struct nci_core_reset_ntf *)skb->data;
+
+	/*
+	 * If the controller reports an unrecoverable error while a reset is
+	 * pending, fail the in-flight reset request.
+	 */
+	if (ntf->reset_trigger == NCI_RESET_TRIGGER_ERROR) {
+		if (test_and_clear_bit(NCI_RESET_PENDING, &ndev->flags))
+			nci_req_complete(ndev, NCI_STATUS_FAILED);
+		return 0;
+	}
+
+	/*
+	 * Only CORE_RESET_CMD-triggered notifications (0x02) complete a
+	 * pending reset request in NCI 2.0. Power-on (0x01) and proprietary
+	 * triggers (>= 0xA0) must not update core protocol state.
+	 */
+	if (ntf->reset_trigger != NCI_RESET_TRIGGER_RESET_CMD)
+		return 0;
+
+	if (!test_and_clear_bit(NCI_RESET_PENDING, &ndev->flags)) {
+		pr_warn_ratelimited("unexpected CORE_RESET_NTF\n");
+		return 0;
+	}
+
+	if (skb->len < offsetofend(struct nci_core_reset_ntf,
+				   manufacturer_specific_len)) {
+		nci_req_complete(ndev, NCI_STATUS_FAILED);
+		return 0;
+	}
 
 	ndev->nci_ver = ntf->nci_ver;
 	pr_debug("nci_ver 0x%x, config_status 0x%x\n",
 		 ntf->nci_ver, ntf->config_status);
 
 	ndev->manufact_id = ntf->manufact_id;
-	ndev->manufact_specific_info =
-		__le32_to_cpu(ntf->manufact_specific_info);
+	if (ntf->manufacturer_specific_len >= sizeof(__le32) &&
+	    skb->len >= sizeof(struct nci_core_reset_ntf))
+		ndev->manufact_specific_info =
+			__le32_to_cpu(ntf->manufact_specific_info);
+	else
+		ndev->manufact_specific_info = 0;
 
 	nci_req_complete(ndev, NCI_STATUS_OK);
 
diff --git a/net/nfc/nci/rsp.c b/net/nfc/nci/rsp.c
index b0ab4f5acbce..7a3c6bc1a0da 100644
--- a/net/nfc/nci/rsp.c
+++ b/net/nfc/nci/rsp.c
@@ -32,16 +32,32 @@ static void nci_core_reset_rsp_packet(struct nci_dev *ndev,
 
 	pr_debug("status 0x%x\n", rsp->status);
 
-	/* Handle NCI 1.x ver */
-	if (skb->len != 1) {
-		if (rsp->status == NCI_STATUS_OK) {
-			ndev->nci_ver = rsp->nci_ver;
-			pr_debug("nci_ver 0x%x, config_status 0x%x\n",
-				 rsp->nci_ver, rsp->config_status);
-		}
+	/*
+	 * If no reset request is pending, ignore unexpected responses to avoid
+	 * prematurely completing an unrelated request.
+	 */
+	if (!test_bit(NCI_RESET_PENDING, &ndev->flags))
+		return;
+
+	if (rsp->status != NCI_STATUS_OK) {
+		if (test_and_clear_bit(NCI_RESET_PENDING, &ndev->flags))
+			nci_req_complete(ndev, rsp->status);
+		return;
+	}
+
+	/* Handle NCI 1.x ver: completed by RSP */
+	if (skb->len >= sizeof(*rsp)) {
+		if (!test_and_clear_bit(NCI_RESET_PENDING, &ndev->flags))
+			return;
+
+		ndev->nci_ver = rsp->nci_ver;
+		pr_debug("nci_ver 0x%x, config_status 0x%x\n",
+			 rsp->nci_ver, rsp->config_status);
 
 		nci_req_complete(ndev, rsp->status);
 	}
+
+	/* NCI 2.x ver: status is OK, wait for CORE_RESET_NTF to complete */
 }
 
 static u8 nci_core_init_rsp_packet_v1(struct nci_dev *ndev,
-- 
2.53.0