linux-kernel - [PATCH] NFC: st21nfca,st-nci: fix use of uninitialized variables in error path

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Date:	Mon, 29 Jun 2015 18:17:54 +0800
From:	Nicolas Iooss <nicolas.iooss_linux@....org>
To:	Lauro Ramos Venancio <lauro.venancio@...nbossa.org>,
	Aloisio Almeida Jr <aloisio.almeida@...nbossa.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Christophe Ricard <christophe.ricard@...il.com>
Cc:	linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
	Nicolas Iooss <nicolas.iooss_linux@....org>
Subject: [PATCH] NFC: st21nfca,st-nci: fix use of uninitialized variables in error path

st21nfca_hci_load_session() calls kfree_skb() on unitialized variables
skb_pipe_info and skb_pipe_list if the call to nfc_hci_connect_gate()
failed.  Reword the error path to not use these variables when they are
not initialized.  While at it, there seemed to be a memory leak because
skb_pipe_info was only freed once, after the for-loop, even though
several ones were created by nfc_hci_send_cmd.

st_nci_hci_load_session() is similar to st21nfca_hci_load_session(), so
rework this function too.

Fixes: ec03ff1a8f9a ("NFC: st21nfca: Remove skb_pipe_list and skb_pipe_info
useless allocation")

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@....org>
---

As I haven't got the hardware needed to perform tests, I only compile-tested
this patch.

Moreover I may then have missed something important for example in the way
the memory is managed (I did not understand why skb_pipe_info was not freed
in the for loop).

 drivers/nfc/st-nci/st-nci_se.c  |  8 ++++----
 drivers/nfc/st21nfca/st21nfca.c | 11 ++++++-----
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/nfc/st-nci/st-nci_se.c b/drivers/nfc/st-nci/st-nci_se.c
index 97addfa96c6f..c742ef65a05a 100644
--- a/drivers/nfc/st-nci/st-nci_se.c
+++ b/drivers/nfc/st-nci/st-nci_se.c
@@ -189,14 +189,14 @@ int st_nci_hci_load_session(struct nci_dev *ndev)
 				ST_NCI_DEVICE_MGNT_GATE,
 				ST_NCI_DEVICE_MGNT_PIPE);
 	if (r < 0)
-		goto free_info;
+		return r;
 
 	/* Get pipe list */
 	r = nci_hci_send_cmd(ndev, ST_NCI_DEVICE_MGNT_GATE,
 			ST_NCI_DM_GETINFO, pipe_list, sizeof(pipe_list),
 			&skb_pipe_list);
 	if (r < 0)
-		goto free_info;
+		return r;
 
 	/* Complete the existing gate_pipe table */
 	for (i = 0; i < skb_pipe_list->len; i++) {
@@ -222,6 +222,7 @@ int st_nci_hci_load_session(struct nci_dev *ndev)
 		    dm_pipe_info->src_host_id != ST_NCI_ESE_HOST_ID) {
 			pr_err("Unexpected apdu_reader pipe on host %x\n",
 			       dm_pipe_info->src_host_id);
+			kfree_skb(skb_pipe_info);
 			continue;
 		}
 
@@ -241,13 +242,12 @@ int st_nci_hci_load_session(struct nci_dev *ndev)
 			ndev->hci_dev->pipes[st_nci_gates[j].pipe].host =
 						dm_pipe_info->src_host_id;
 		}
+		kfree_skb(skb_pipe_info);
 	}
 
 	memcpy(ndev->hci_dev->init_data.gates, st_nci_gates,
 	       sizeof(st_nci_gates));
 
-free_info:
-	kfree_skb(skb_pipe_info);
 	kfree_skb(skb_pipe_list);
 	return r;
 }
diff --git a/drivers/nfc/st21nfca/st21nfca.c b/drivers/nfc/st21nfca/st21nfca.c
index d251f7229c4e..051286562fab 100644
--- a/drivers/nfc/st21nfca/st21nfca.c
+++ b/drivers/nfc/st21nfca/st21nfca.c
@@ -148,14 +148,14 @@ static int st21nfca_hci_load_session(struct nfc_hci_dev *hdev)
 				ST21NFCA_DEVICE_MGNT_GATE,
 				ST21NFCA_DEVICE_MGNT_PIPE);
 	if (r < 0)
-		goto free_info;
+		return r;
 
 	/* Get pipe list */
 	r = nfc_hci_send_cmd(hdev, ST21NFCA_DEVICE_MGNT_GATE,
 			ST21NFCA_DM_GETINFO, pipe_list, sizeof(pipe_list),
 			&skb_pipe_list);
 	if (r < 0)
-		goto free_info;
+		return r;
 
 	/* Complete the existing gate_pipe table */
 	for (i = 0; i < skb_pipe_list->len; i++) {
@@ -181,6 +181,7 @@ static int st21nfca_hci_load_session(struct nfc_hci_dev *hdev)
 			info->src_host_id != ST21NFCA_ESE_HOST_ID) {
 			pr_err("Unexpected apdu_reader pipe on host %x\n",
 				info->src_host_id);
+			kfree_skb(skb_pipe_info);
 			continue;
 		}
 
@@ -200,6 +201,7 @@ static int st21nfca_hci_load_session(struct nfc_hci_dev *hdev)
 			hdev->pipes[st21nfca_gates[j].pipe].dest_host =
 							info->src_host_id;
 		}
+		kfree_skb(skb_pipe_info);
 	}
 
 	/*
@@ -214,13 +216,12 @@ static int st21nfca_hci_load_session(struct nfc_hci_dev *hdev)
 					st21nfca_gates[i].gate,
 					st21nfca_gates[i].pipe);
 			if (r < 0)
-				goto free_info;
+				goto free_list;
 		}
 	}
 
 	memcpy(hdev->init_data.gates, st21nfca_gates, sizeof(st21nfca_gates));
-free_info:
-	kfree_skb(skb_pipe_info);
+free_list:
 	kfree_skb(skb_pipe_list);
 	return r;
 }
-- 
2.4.4

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