From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Date: Thu, 31 Jan 2013 08:16:46 +0000 Subject: [patch] NFC: llcp: integer underflow in nfc_llcp_set_remote_gb() Message-Id: <20130131081645.GA14812@elgon.mountain> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Lauro Ramos Venancio Cc: Aloisio Almeida Jr , Samuel Ortiz , "David S. Miller" , "John W. Linville" , Thierry Escande , Szymon Janc , linux-wireless@vger.kernel.org, linux-nfc@ml01.01.org, netdev@vger.kernel.org, kernel-janitors@vger.kernel.org If gb_len is less than 3 it would cause an integer underflow and possibly memory corruption in nfc_llcp_parse_gb_tlv(). I removed the old test for gb_len = 0. I also removed the test for ->remote_gb = NULL. It's not possible for ->remote_gb to be NULL and we have already dereferenced ->remote_gb_len so it's too late to test. The old test return -ENODEV but my test returns -EINVAL. Signed-off-by: Dan Carpenter diff --git a/net/nfc/llcp/llcp.c b/net/nfc/llcp/llcp.c index 85bc75c..746f5a2 100644 --- a/net/nfc/llcp/llcp.c +++ b/net/nfc/llcp/llcp.c @@ -549,14 +549,13 @@ int nfc_llcp_set_remote_gb(struct nfc_dev *dev, u8 *gb, u8 gb_len) pr_err("No LLCP device\n"); return -ENODEV; } + if (gb_len < 3) + return -EINVAL; memset(local->remote_gb, 0, NFC_MAX_GT_LEN); memcpy(local->remote_gb, gb, gb_len); local->remote_gb_len = gb_len; - if (local->remote_gb = NULL || local->remote_gb_len = 0) - return -ENODEV; - if (memcmp(local->remote_gb, llcp_magic, 3)) { pr_err("MAC does not support LLCP\n"); return -EINVAL;