Patchwork Bluetooth: Prevent buffer overflow in l2cap config request

login
register
mail settings
Submitter Dan Rosenberg
Date June 24, 2011, 12:38 p.m.
Message ID <1308919085.5295.11.camel@dan>
Download mbox | patch
Permalink /patch/101783/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Dan Rosenberg - June 24, 2011, 12:38 p.m.
A remote user can provide a small value for the command size field in
the command header of an l2cap configuration request, resulting in an
integer underflow when subtracting the size of the configuration request
header.  This results in copying a very large amount of data via
memcpy() and destroying the kernel heap.  Check for underflow.

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: stable <stable@kernel.org>
---
 net/bluetooth/l2cap_core.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)



--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Gustavo F. Padovan - June 28, 2011, 5:59 p.m.
Hi Dan,

* Dan Rosenberg <drosenberg@vsecurity.com> [2011-06-24 08:38:05 -0400]:

> A remote user can provide a small value for the command size field in
> the command header of an l2cap configuration request, resulting in an
> integer underflow when subtracting the size of the configuration request
> header.  This results in copying a very large amount of data via
> memcpy() and destroying the kernel heap.  Check for underflow.
> 
> Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
> Cc: stable <stable@kernel.org>
> ---
>  net/bluetooth/l2cap_core.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)

Applied, thanks.

	Gustavo
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index e64a1c2..06ea272 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -2334,7 +2334,7 @@  static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
 
 	/* Reject if config buffer is too small. */
 	len = cmd_len - sizeof(*req);
-	if (chan->conf_len + len > sizeof(chan->conf_req)) {
+	if (len < 0 || chan->conf_len + len > sizeof(chan->conf_req)) {
 		l2cap_send_cmd(conn, cmd->ident, L2CAP_CONF_RSP,
 				l2cap_build_conf_rsp(chan, rsp,
 					L2CAP_CONF_REJECT, flags), rsp);