Subject: [PATCH v2] drivers/net/cxgb3/cxgb3_main.c: prevent reading uninitialized stack memory

From: Dan Rosenberg <[email-masked]>
Date: Wed, 15 Sep 2010 17:43:12 -0400

Fixed formatting (tabs and line breaks).

The CHELSIO_GET_QSET_NUM device ioctl allows unprivileged users to read
4 bytes of uninitialized stack memory, because the "addr" member of the
ch_reg struct declared on the stack in cxgb_extension_ioctl() is not
altered or zeroed before being copied back to the user.  This patch
takes care of it.

Signed-off-by: Dan Rosenberg <[email-masked]>

--- linux-2.6.35.4.orig/drivers/net/cxgb3/cxgb3_main.c	2010-08-26 19:47:12.000000000 -0400
+++ linux-2.6.35.4/drivers/net/cxgb3/cxgb3_main.c	2010-09-14 21:24:34.369511115 -0400
@@ -2296,6 +2296,8 @@ static int cxgb_extension_ioctl(struct n
 	case CHELSIO_GET_QSET_NUM:{
 		struct ch_reg edata;
 
+		memset(&edata, 0, sizeof(struct ch_reg));
+
 		edata.cmd = CHELSIO_GET_QSET_NUM;
 		edata.val = pi->nqsets;
 		if (copy_to_user(useraddr, &edata, sizeof(edata)))