netdev - [PATCH v3] nfc: virtual_ncidev: Fix memory leak in virtual_nci

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Message-ID: <20221020030505.15572-1-shangxiaojing@huawei.com>
Date:   Thu, 20 Oct 2022 11:05:05 +0800
From:   Shang XiaoJing <shangxiaojing@...wei.com>
To:     <bongsu.jeon@...sung.com>, <krzysztof.kozlowski@...aro.org>,
        <kuba@...nel.org>, <pabeni@...hat.com>, <netdev@...r.kernel.org>
CC:     <shangxiaojing@...wei.com>
Subject: [PATCH v3] nfc: virtual_ncidev: Fix memory leak in virtual_nci_send()

skb should be free in virtual_nci_send(), otherwise kmemleak will report
memleak.

Steps for reproduction (simulated in qemu):
	cd tools/testing/selftests/nci
	make
	./nci_dev

BUG: memory leak
unreferenced object 0xffff888107588000 (size 208):
  comm "nci_dev", pid 206, jiffies 4294945376 (age 368.248s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000008d94c8fd>] __alloc_skb+0x1da/0x290
    [<00000000278bc7f8>] nci_send_cmd+0xa3/0x350
    [<0000000081256a22>] nci_reset_req+0x6b/0xa0
    [<000000009e721112>] __nci_request+0x90/0x250
    [<000000005d556e59>] nci_dev_up+0x217/0x5b0
    [<00000000e618ce62>] nfc_dev_up+0x114/0x220
    [<00000000981e226b>] nfc_genl_dev_up+0x94/0xe0
    [<000000009bb03517>] genl_family_rcv_msg_doit.isra.14+0x228/0x2d0
    [<00000000b7f8c101>] genl_rcv_msg+0x35c/0x640
    [<00000000c94075ff>] netlink_rcv_skb+0x11e/0x350
    [<00000000440cfb1e>] genl_rcv+0x24/0x40
    [<0000000062593b40>] netlink_unicast+0x43f/0x640
    [<000000001d0b13cc>] netlink_sendmsg+0x73a/0xbf0
    [<000000003272487f>] __sys_sendto+0x324/0x370
    [<00000000ef9f1747>] __x64_sys_sendto+0xdd/0x1b0
    [<000000001e437841>] do_syscall_64+0x3f/0x90

Fixes: e624e6c3e777 ("nfc: Add a virtual nci device driver")
Signed-off-by: Shang XiaoJing <shangxiaojing@...wei.com>
---
changes in v2:
- free skb in error paths too.
changes in v3:
- change consume_skb() to kfree_skb() in error paths.
---
 drivers/nfc/virtual_ncidev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/nfc/virtual_ncidev.c b/drivers/nfc/virtual_ncidev.c
index f577449e4935..85c06dbb2c44 100644
--- a/drivers/nfc/virtual_ncidev.c
+++ b/drivers/nfc/virtual_ncidev.c
@@ -54,16 +54,19 @@ static int virtual_nci_send(struct nci_dev *ndev, struct sk_buff *skb)
 	mutex_lock(&nci_mutex);
 	if (state != virtual_ncidev_enabled) {
 		mutex_unlock(&nci_mutex);
+		kfree_skb(skb);
 		return 0;
 	}
 
 	if (send_buff) {
 		mutex_unlock(&nci_mutex);
+		kfree_skb(skb);
 		return -1;
 	}
 	send_buff = skb_copy(skb, GFP_KERNEL);
 	mutex_unlock(&nci_mutex);
 	wake_up_interruptible(&wq);
+	consume_skb(skb);
 
 	return 0;
 }
-- 
2.17.1