Linux kernel staging patches
 help / color / Atom feed
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Won Kang <wkang77@gmail.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>,
	linux-staging@lists.linux.dev, kernel-janitors@vger.kernel.org
Subject: [PATCH 2/2] staging: gdm724x: check for overflow in gdm_lte_netif_rx()
Date: Mon, 14 Jun 2021 12:58:36 +0300
Message-ID: <YMcoTPsCYlhh2TQo@mwanda> (raw)
In-Reply-To: <YMcnl4zCwGWGDVMG@mwanda>

This code assumes that "len" is at least 62 bytes, but we need a check
to prevent a read overflow.

Fixes: 61e121047645 ("staging: gdm7240: adding LTE USB driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
There is a different place that does:

	ip_version = buf[0] >> 4;

Which assumes that "len" is one.  I think that should be checked in the
caller...  I didn't add a check here because I think it's the wrong
place but then I didn't add a check in the caller because I wasn't able
to test it.  I'm not really that worried about reading one element
beyond the end of the buffer.  If we get extremely unlucky it could
result in a crash...  Hopefully we will remember to look at this again
before moving this code out of staging.

#TODO:

 drivers/staging/gdm724x/gdm_lte.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/gdm724x/gdm_lte.c b/drivers/staging/gdm724x/gdm_lte.c
index a41af7aa74ec..bd5f87433404 100644
--- a/drivers/staging/gdm724x/gdm_lte.c
+++ b/drivers/staging/gdm724x/gdm_lte.c
@@ -611,10 +611,12 @@ static void gdm_lte_netif_rx(struct net_device *dev, char *buf,
 						  * bytes (99,130,83,99 dec)
 						  */
 			} __packed;
-			void *addr = buf + sizeof(struct iphdr) +
-				sizeof(struct udphdr) +
-				offsetof(struct dhcp_packet, chaddr);
-			ether_addr_copy(nic->dest_mac_addr, addr);
+			int offset = sizeof(struct iphdr) +
+				     sizeof(struct udphdr) +
+				     offsetof(struct dhcp_packet, chaddr);
+			if (offset + ETH_ALEN > len)
+				return;
+			ether_addr_copy(nic->dest_mac_addr, buf + offset);
 		}
 	}
 
-- 
2.30.2


      reply index

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-14  9:55 [PATCH 1/2] staging: gdm724x: check for buffer overflow in gdm_lte_multi_sdu_pkt() Dan Carpenter
2021-06-14  9:58 ` Dan Carpenter [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YMcoTPsCYlhh2TQo@mwanda \
    --to=dan.carpenter@oracle.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=gustavoars@kernel.org \
    --cc=kernel-janitors@vger.kernel.org \
    --cc=linux-staging@lists.linux.dev \
    --cc=wkang77@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux kernel staging patches

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-staging/0 linux-staging/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-staging linux-staging/ https://lore.kernel.org/linux-staging \
		linux-staging@lists.linux.dev
	public-inbox-index linux-staging

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/dev.linux.lists.linux-staging


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git